bluuebunny/crossref_metadata_2025 huggingface dataset:
Prevention‐oriented practice of Iranian senior dental students
Authors: Khami Mohammad R. , Virtanen Jorma I. , Jafarian Mohammad , Murtomaa Heikki
Published: January 2007

Objectives:  To investigate self‐reported preventive practice of Iranian senior dental students in dental caries management.

Subjects and methods:  To obtain an estimated sample size of 250 subjects, seven state dental schools were selected based on a stratified random sampling approach. All the senior dental students (n = 327) were asked to voluntarily fill in a self‐administered pre‐tested questionnaire during the spring term in 2005. In the questionnaire two hypothetical patient cases (a high‐risk and a low‐risk patient) were presented and the students were asked to express their conceptions on a five‐point Likert scale about including each of nine given alternatives in the patients’ treatment plans. The respondents’ self‐reported oral self‐care (OSC), preventive knowledge, attitude towards prevention and self‐perceived competency in giving preventive care were also assessed. Chi‐squared test and logistic regression model served for statistical analyses.

Results:  A total of 270 students filled in the questionnaire (response rate = 82%). Acquiring high scores of preventive practice as assessed by patient cases was found to be more frequent among those reporting recommended OSC (P = 0.007) and those with higher attitude scores (P < 0.001). Also, those reporting being competent in giving preventive care had higher scores of preventive practice compared with the others (P = 0.02). In the regression model, recommended OSC (P = 0.05, OR = 1.9) and positive attitudes towards preventive dentistry (P = 0.001, OR = 3.3) showed significant association with acquiring highest scores of preventive practice.

Conclusion:  To improve their preventive practice in the future, more emphasis should be placed on the dental students’ own oral health behaviour and attitudes related to it.
INSPIRE: A VLF Radio Project for High School Students
Authors: Marshall Jill A. , Pine Bill , Taylor William W. L.
Published: January 2007

Since 1988 the Interactive NASA Space Physics Ionospheric Radio Experiment, or INSPIRE,1 has given students the opportunity to build research-quality VLF2 radio receivers and make observations of both natural and stimulated radio waves in the atmosphere. Any high school science class is eligible to join the INSPIRE volunteer observing network and contribute to our understanding of near-Earth space.
In Vitro Activity of Aurein 1.2 Alone and in Combination with Antibiotics against Gram-Positive Nosocomial Cocci
Authors: Giacometti Andrea , Cirioni Oscar , Riva Alessandra , Kamysz Wojciech , Silvestri Carmela , Nadolski Piotr , Della Vittoria Agnese , Łukasiak Jerzy , Scalise Giorgio
Published: January 2007

This study was performed to evaluate the in vitro activity of the amphibian peptide aurein 1.2 and to investigate its interaction with six antibiotics against nosocomial gram-positive cocci. All isolates were inhibited at concentrations of 1 to 16 mg/liter. Synergy was demonstrated when aurein 1.2 was combined with clarithromycin and minocycline.
First Report of Plasmid-Mediated
qnrA1
in a Ciprofloxacin-Resistant
Escherichia coli
Strain in Latin America
Authors: Castanheira Mariana , Pereira Andrea S. , Nicoletti Adriana G. , Pignatari Antônio C. C. , Barth Afonso L. , Gales Ana C.
Published: January 2007

Among 144 ciprofloxacin-resistant
Escherichia coli
isolated in Brazil, one (0.69%) QnrA1-producing isolate was detected. The
qnrA1
gene was associated with IS
CR1
. The QnrA1 determinant was carried on a 41-kb conjugative plasmid, which also carried a FOX-type cephalosporinase encoding gene and a class 1 integron with the
aadB
and
catB3
cassettes. This is the first report of a
qnrA
-carrying isolate in a Latin American country.
Combination of Tigecycline and
N
-Acetylcysteine Reduces Biofilm-Embedded Bacteria on Vascular Catheters
Authors: Aslam Saima , Trautner Barbara W. , Ramanathan Venkat , Darouiche Rabih O.
Published: January 2007

To assess the efficacy of an antibiofilm/antimicrobial agent combination, we incubated catheter segments colonized with one of six studied bacterial organisms in
N
-acetylcysteine, tigecycline,
N
-acetylcysteine-tigecycline, or saline. Segments were washed, sonicated, and cultured.
N
-acetylcysteine-tigecycline significantly decreased all viable biofilm-associated bacteria and was synergistic for methicillin-resistant
Staphylococcus aureus
and
Staphylococcus epidermidis
.
Genetics and Expression of the Carbapenem-Hydrolyzing Oxacillinase GeneblaOXA-23inAcinetobacter baumannii
Authors: Corvec Stéphane , Poirel Laurent , Naas Thierry , Drugeon Henri , Nordmann Patrice
Published: January 2007

The genetic structures surrounding the plasmid-carriedblaOXA-23oxacillinase gene, encoding resistance to carbapenems, were studied inAcinetobacter baumannii. ISAba1and the novel element ISAba4were detected upstream of theblaOXA-23gene, providing promoter sequences for its expression. These insertion elements were likely involved in transposition processes at the origin of acquisition of this β-lactamase gene.
Zidovudine Inhibits Thymidine Phosphorylation in the Isolated Perfused Rat Heart
Authors: Susan-Resiga Delia , Bentley Alice T. , Lynx Matthew D. , LaClair Darcy D. , McKee Edward E.
Published: January 2007

Zidovudine (AZT; 3′-azido-3′-deoxythymidine), a thymidine analog, has been a staple of highly active antiretroviral therapy. It is phosphorylated in the host to the triphosphate and functions by inhibiting the viral reverse transcriptase. However, long-term use of AZT is linked to various tissue toxicities, including cardiomyopathy. These toxicities are associated with mitochondrial DNA depletion, which is hypothesized to be caused by AZT triphosphate inhibition of mitochondrial DNA polymerase γ. In previous work with isolated heart mitochondria, we demonstrated that AZT phosphorylation beyond the monophosphate was not detected and that AZT itself was a potent inhibitor of thymidine phosphorylation. This suggests an alternative hypothesis in which depletion of the TTP pool may limit mitochondrial DNA replication. The present work extends these studies to the whole cell by investigating the metabolism of thymidine and AZT in the intact isolated perfused rat heart. [3H]thymidine is converted to [3H]TTP in a time- and concentration-dependent manner. The level of [3H]TMP is low, suggesting that the reaction catalyzed by thymidine kinase is the rate-limiting step in phosphorylation. [3H]AZT is converted in a time- and concentration-dependent manner to AZT monophosphate, the only phosphorylated product detected after 3 h of perfusion. Both compounds display negative cooperativity, similar to the observations with cloned and purified mitochondrial thymidine kinase 2. The presence of AZT in the perfusate inhibits the phosphorylation of [3H]thymidine with a 50% inhibitory concentration of 24 ± 4 μM. These data support the hypothesis that AZT-induced mitochondrial cardiotoxicity may be caused by a limiting pool of TTP that lowers mitochondrial DNA replication.
Activity of Daptomycin Alone and in Combination with Rifampin and Gentamicin against
Staphylococcus aureus
Assessed by Time-Kill Methodology
Authors: Credito Kim , Lin Gengrong , Appelbaum Peter C.
Published: January 2007

The synergistic effects of daptomycin plus gentamicin or rifampin were tested against 50
Staphylococcus aureus
strains, with daptomycin MICs ranging between 0.25 and 8 μg/ml. Daptomycin sub-MICs combined with gentamicin concentrations lower than the MIC yielded synergy in 34 (68%) of the 50 strains. Daptomycin combined with rifampin yielded synergy in one vancomycin-intermediate
S. aureus
strain only, and virtually all synergy occurred between daptomycin and gentamicin.
Rectoanal Junction Colonization of Feedlot Cattle by
Escherichia coli
O157:H7 and Its Association with Supershedders and Excretion Dynamics
Authors: Cobbold Rowland N. , Hancock Dale D. , Rice Daniel H. , Berg Janice , Stilborn Robert , Hovde Carolyn J. , Besser Thomas E.
Published: January 2007

Feedlot cattle were observed for fecal excretion of and rectoanal junction (RAJ) colonization with
Escherichia coli
O157:H7 to identify potential “supershedders.” RAJ colonization and fecal excretion prevalences were correlated, and
E. coli
O157:H7 prevalences and counts were significantly greater for RAJ samples. Based on a comparison of RAJ and fecal ratios of
E. coli
O157:H7/
E. coli
counts, the RAJ appears to be preferentially colonized by the O157:H7 serotype. Five supershedders were identified based on persistent colonization with high concentrations of
E. coli
O157:H7. Cattle copenned with supershedders had significantly greater mean pen
E. coli
O157:H7 RAJ and fecal prevalences than noncopenned cattle. Cumulative fecal
E. coli
O157:H7 excretion was also significantly higher for pens housing a supershedder.
E. coli
O157:H7/
E. coli
count ratios were higher for supershedders than for other cattle, indicating greater proportional colonization. Pulsed-field gel electrophoresis analysis demonstrated that isolates from supershedders and copenned cattle were highly related. Cattle that remained negative for
E. coli
O157:H7 throughout sampling were five times more likely to have been in a pen that did not house a supershedder. The data from this study support an association between levels of fecal excretion of
E. coli
O157:H7 and RAJ colonization in pens of feedlot cattle and suggest that the presence of supershedders influences group-level excretion parameters. An improved understanding of individual and population transmission dynamics of
E. coli
O157:H7 can be used to develop preslaughter- and slaughter-level interventions that reduce contamination of the food chain.
The Presence of the Internalin Gene in Natural Atypically Hemolytic
Listeria innocua
Strains Suggests Descent from
L. monocytogenes
Authors: Volokhov Dmitriy V. , Duperrier Sandra , Neverov Alexander A. , George Joseph , Buchrieser Carmen , Hitchins Anthony D.
Published: January 2007

The atypical hemolytic
Listeria innocua
strains PRL/NW 15B95 and J1-023 were previously shown to contain gene clusters analogous to the pathogenicity island (LIPI-1) present in the related foodborne gram-positive facultative intracellular pathogen
Listeria monocytogenes
, which causes listeriosis. LIPI-1 includes the hemolysin gene, thus explaining the hemolytic activity of the atypical
L. innocua
strains. No other
L. monocytogenes
-specific virulence genes were found to be present. In order to investigate whether any other specific
L. monocytogenes
genes could be identified, a global approach using a
Listeria
biodiversity DNA array was applied. According to the hybridization results, the isolates were defined as
L. innocua
strains containing LIPI-1. Surprisingly, evidence for the presence of the
L. monocytogenes
-specific
inlA
gene, previously thought to be absent, was obtained. The
inlA
gene codes for the InlA protein which enables bacterial entry into some nonprofessional phagocytic cells. PCR and sequence analysis of this region revealed that the flanking genes of the
inlA
gene at the upstream, 5′-end region were similar to genes found in
L. monocytogenes
serotype 4b isolates, whereas the organization of the downstream, 3′-end region was similar to that typical of
L. innocua
. Sequencing of the
inlA
region identified a small stretch reminiscent of the
inlB
gene of
L. monocytogenes
. The presence of two clusters of
L. monocytogenes
-specific genes makes it unlikely that PRL/NW 15B95 and J1-023 are
L. innocua
strains altered by horizontal transfer. It is more likely that they are distinct relics of the evolution of
L. innocua
from an ancestral
L. monocytogenes
, as postulated by others.
A Portable Anaerobic Microbioreactor Reveals Optimum Growth Conditions for the Methanogen
Methanosaeta concilii
Authors: Steinhaus Benjamin , Garcia Marcelo L. , Shen Amy Q. , Angenent Largus T.
Published: January 2007

Conventional studies of the optimum growth conditions for methanogens (methane-producing, obligate anaerobic archaea) are typically conducted with serum bottles or bioreactors. The use of microfluidics to culture methanogens allows direct microscopic observations of the time-integrated response of growth. Here, we developed a microbioreactor (μBR) with ∼1-μl microchannels to study some optimum growth conditions for the methanogen
Methanosaeta concilii
. The μBR is contained in an anaerobic chamber specifically designed to place it directly onto an inverted light microscope stage while maintaining a N
2
-CO
2
environment. The methanogen was cultured for months inside microchannels of different widths. Channel width was manipulated to create various fluid velocities, allowing the direct study of the behavior and responses of
M. concilii
to various shear stresses and revealing an optimum shear level of ∼20 to 35 μPa. Gradients in a single microchannel were then used to find an optimum pH level of 7.6 and an optimum total NH
4
-N concentration of less than 1,100 mg/liter (<47 mg/liter as free NH
3
-N) for
M. concilii
under conditions of the previously determined ideal shear stress and pH and at a temperature of 35°C.
Recombinant Polycistronic Structure of Hydantoinase Process Genes in
Escherichia coli
for the Production of Optically Pure
d
-Amino Acids
Authors: Martínez-Gómez Ana Isabel , Martínez-Rodríguez Sergio , Clemente-Jiménez Josefa María , Pozo-Dengra Joaquín , Rodríguez-Vico Felipe , Las Heras-Vázquez Francisco Javier
Published: January 2007

Two recombinant reaction systems for the production of optically pure
d
-amino acids from different
d,l
-5-monosubstituted hydantoins were constructed. Each system contained three enzymes, two of which were
d
-hydantoinase and
d
-carbamoylase from
Agrobacterium tumefaciens
BQL9. The third enzyme was hydantoin racemase 1 for the first system and hydantoin racemase 2 for the second system, both from
A. tumefaciens
C58. Each system was formed by using a recombinant
Escherichia coli
strain with one plasmid harboring three genes coexpressed with one promoter in a polycistronic structure. The
d
-carbamoylase gene was cloned closest to the promoter in order to obtain the highest level of synthesis of the enzyme, thus avoiding intermediate accumulation, which decreases the reaction rate. Both systems were able to produce 100% conversion and 100% optically pure
d
-methionine,
d
-leucine,
d
-norleucine,
d
-norvaline,
d
-aminobutyric acid,
d
-valine,
d
-phenylalanine,
d
-tyrosine, and
d
-tryptophan from the corresponding hydantoin racemic mixture. For the production of almost all
d
-amino acids studied in this work, system 1 hydrolyzed the 5-monosubstituted hydantoins faster than system 2.
Use of Bimolecular Fluorescence Complementation To Study In Vivo Interactions between Cdc42p and Rdi1p of
Saccharomyces cerevisiae
Authors: Cole Karen C. , McLaughlin Heather W. , Johnson Douglas I.
Published: January 2007

Saccharomyces cerevisiae
Cdc42p functions as a GTPase molecular switch, activating multiple signaling pathways required to regulate cell cycle progression and the actin cytoskeleton. Regulatory proteins control its GTP binding and hydrolysis and its subcellular localization, ensuring that Cdc42p is appropriately activated and localized at sites of polarized growth during the cell cycle. One of these, the Rdi1p guanine nucleotide dissociation inhibitor, negatively regulates Cdc42p by extracting it from cellular membranes. In this study, the technique of bimolecular fluorescence complementation (BiFC) was used to study the dynamic in vivo interactions between Cdc42p and Rdi1p. The BiFC data indicated that Cdc42p and Rdi1p interacted in the cytoplasm and around the periphery of the cell at the plasma membrane and that this interaction was enhanced at sites of polarized cell growth during the cell cycle, i.e., incipient bud sites, tips and sides of small- and medium-sized buds, and the mother-bud neck region. In addition, a ring-like structure containing the Cdc42p-Rdi1p complex transiently appeared following release from G
1
-phase cell cycle arrest. A homology model of the Cdc42p-Rdi1p complex was used to introduce mutations that were predicted to affect complex formation. These mutations resulted in altered BiFC interactions, restricting the complex exclusively to either the plasma membrane or the cytoplasm. Data from these studies have facilitated the temporal and spatial modeling of Rdi1p-dependent extraction of Cdc42p from the plasma membrane during the cell cycle.
Potential Role for Toll-Like Receptor 4 in Mediating
Escherichia coli
Maltose-Binding Protein Activation of Dendritic Cells
Authors: Fernandez Stefan , Palmer Dupeh R. , Simmons Monika , Sun Peifang , Bisbing John , McClain Sasha , Mani Sachin , Burgess Timothy , Gunther Vicky , Sun Wellington
Published: January 2007

The
Escherichia coli
maltose-binding protein (MBP) is used to increase the stability and solubility of proteins in bacterial protein expression systems and is increasingly being used to facilitate the production and delivery of subunit vaccines against various pathogenic bacteria and viruses. The MBP tag is presumed inert, with minimum effects on the bioactivity of the tagged protein or its biodistribution. However, few studies have characterized the immunological attributes of MBP. Here, we analyze the phenotypic and functional outcomes of MBP-treated dendritic cells (DCs) and show that MBP induces DC activation and production of proinflammatory cytokines (interleukin-1β [IL-1β], IL-6, IL-8, tumor necrosis factor alpha, and IL-12p70) within 24 h and strongly increases Iκβ phosphorylation in treated cells. Interestingly, phosphorylation of Iκβ was largely abrogated by the addition of anti-human Toll-like receptor 4 (TLR4) antibodies, indicating that MBP activates signaling for DC maturation via TLR4. Consistent with this hypothesis, MBP activated the TLR4-expressing cell line 293-hTLR4A but not control cultures to secrete IL-8. The observed data were independent of lipopolysaccharide contamination and support a role for TLR4 in mediating the effects of MBP. These results provide insight into a mechanism by which MBP might enhance immune responses to vaccine fusion proteins.
SiiE Is Secreted by the
Salmonella enterica
Serovar Typhimurium Pathogenicity Island 4-Encoded Secretion System and Contributes to Intestinal Colonization in Cattle
Authors: Morgan Eirwen , Bowen Alison J. , Carnell Sonya C. , Wallis Timothy S. , Stevens Mark P.
Published: January 2007

Here we report that
Salmonella enterica
serovar Typhimurium pathogenicity island 4 carries a type I secretion system (
siiCDF
) which secretes an ∼600-kDa protein (encoded by
siiE
). SiiE is surface expressed, and its production is regulated by HilA. SiiE and SiiF influence colonization in cattle and the invasion of bovine enterocytes.
Interleukin-12 Drives the Th1 Signaling Pathway inHelicobacter pylori-Infected Human Gastric Mucosa
Authors: Pellicanò Antonia , Sebkova Ladislava , Monteleone Giovanni , Guarnieri Giovanni , Imeneo Maria , Pallone Francesco , Luzza Francesco
Published: January 2007

In this study we examined mechanisms that regulate T-helper lymphocyte 1 (Th1) commitment inHelicobacter pylori-infected human gastric mucosa. The levels of gamma interferon (IFN-γ), interleukin-4 (IL-4), and IL-12 in total extracts of gastric biopsies taken fromH. pylori-infected and uninfected patients were determined by an enzyme-linked immunosorbent assay. The levels of signal transducer and activator of transcription 4 (STAT4), STAT6, and T-box expressed in T cells (T-bet) in total proteins extracted from gastric biopsies were determined by Western blotting. Finally, the effect of a neutralizing IL-12 antibody on expression of Th1 transcription factors and the levels of IFN-γ in organ cultures ofH. pylori-infected biopsies was examined. Increased levels of IFN-γ and IL-12 were found in gastric biopsy samples ofH. pylori-infected patients compared to the levels in uninfected patients. In addition,H. pylori-infected biopsies exhibited high levels of expression of phosphorylated STAT4 and T-bet. Higher levels of IFN-γ and expression of Th1 transcription factors were associated with greater infiltration of mononuclear cells in the gastric mucosa. By contrast, production of IL-4 and expression of phosphorylated STAT6 were not associated with the intensity of mononuclear cell infiltration. In ex vivo organ cultures ofH. pylori-infected biopsies, neutralization of endogenous IL-12 down-regulated the expression of phosphorylated STAT4 and T-bet and reduced IFN-γ production. Our data indicated that IL-12 contributes to the Th1 cell commitment inH. pylori-infected human gastric mucosa.
Immunostimulatory Properties of the Emerging Pathogen
Stenotrophomonas maltophilia
Authors: Waters Valerie J. , Gómez Marisa I. , Soong Grace , Amin Sunil , Ernst Robert K. , Prince Alice
Published: January 2007

Stenotrophomonas maltophilia
is a multiple-antibiotic-resistant opportunistic pathogen that is being isolated with increasing frequency from patients with health-care-associated infections and especially from patients with cystic fibrosis (CF). While clinicians feel compelled to treat infections involving this organism, its potential for virulence is not well established. We evaluated the immunostimulatory properties and overall virulence of clinical isolates of
S. maltophilia
using the well-characterized opportunistic pathogen
Pseudomonas aeruginosa
PAO1 as a control. The properties of CF isolates were examined specifically to see if they have a common phenotype. The immunostimulatory properties of
S. maltophilia
were studied in vitro by stimulating airway epithelial and macrophage cell lines. A neonatal mouse model of pneumonia was used to determine the rates of pneumonia, bacteremia, and mortality, as well as the inflammatory response elicited by
S. maltophilia
infection. Respiratory and nonrespiratory
S. maltophilia
isolates were highly immunostimulatory and elicited significant interleukin-8 expression by airway epithelial cells, as well as tumor necrosis factor alpha (TNF-α) expression by macrophages. TNF-α signaling appears to be important in the pathogenesis of
S. maltophilia
infection as less than 20% of TNFR1 null mice (compared with 100% of wild-type mice) developed pneumonia and bacteremia following intranasal inoculation. The
S. maltophilia
isolates were weakly invasive, and low-level bacteremia with no mortality was observed. Despite the lack of invasiveness of
S. maltophilia
, the immunostimulatory properties of this organism and its induction of TNF-α expression specifically indicate that it is likely to contribute significantly to airway inflammation.
Leishmania donovani-Induced Ceramide as the Key Mediator of Akt Dephosphorylation in Murine Macrophages: Role of Protein Kinase Cζ and Phosphatase
Authors: Dey Ranadhir , Majumder Nivedita , Bhattacharjee Surajit , Majumdar Suchandra Bhattacharyya , Banerjee Rajdeep , Ganguly Sandipan , Das Pradeep , Majumdar Subrata
Published: January 2007

Leishmania donovaniis an intracellular protozoan parasite that impairs the host macrophage immune response to render it suitable for its survival and establishment.L. donovani-induced immunosuppression and alteration of host cell signaling is mediated by ceramide, a pleiotropic second messenger playing an important role in regulation of several kinases, including mitogen-activated protein kinase and phosphatases. We observed that the endogenous ceramide generated during leishmanial infection led to the dephosphorylation of protein kinase B (PKB) (Akt) in infected cells. The study of ceramide-mediated Akt phosphorylation revealed that Akt was dephosphorylated at both Thr308 and Ser473 sites in infected cells. Further investigation demonstrated that ceramide was also responsible for the induction of PKCζ, an atypical Ca-independent stress kinase, as well as the ceramide-activated protein phosphatases (e.g., protein phosphatase 2A [PP2A]). We found that Akt dephosphorylation was mediated by ceramide-induced PKCζ-Akt association and PP2A activation. In addition, treatment ofL. donovani-infected macrophages with PKCζ-specific inhibitor peptide could restore the translocation of phosphorylated Akt to the cell membrane. This study also revealed that ceramide is involved in the inhibition of proinflammatory cytokine tumor necrosis factor alpha release by infected macrophages. These observations strongly suggest the importance of ceramide in the alteration of normal cellular functions, impairment of the kinase/phosphatase balance, and thereby establishment of leishmaniasis in the hostile macrophage environment.
Monocyte Chemoattractant Protein 1, Macrophage Inflammatory Protein 1α, and RANTES Recruit Macrophages to the Kidney in a Mouse Model of Hemolytic-Uremic Syndrome
Authors: Keepers Tiffany R. , Gross Lisa K. , Obrig Tom G.
Published: January 2007

The macrophage has previously been implicated in contributing to the renal inflammation associated with hemolytic-uremic syndrome (HUS). However, there is currently no in vivo model detailing the contribution of the renal macrophage to the kidney disease associated with HUS. Therefore, renal macrophage recruitment and inhibition of infiltrating renal macrophages were evaluated in an established HUS mouse model. Macrophage recruitment to the kidney was evident by immunohistochemistry 2 h after administration of purified Stx2 and peaked at 48 h postinjection. Mice administered a combination of Stx2 and lipopolysaccharide (LPS) showed increased macrophage recruitment to the kidney compared to mice treated with Stx2 or LPS alone. Monocyte chemoattractants were induced in the kidney, including monocyte chemoattractant protein 1 (MCP-1/CCL2), macrophage inflammatory protein 1α (MIP-1α/CCL3), and RANTES (CCL5), in a pattern that was coincident with macrophage infiltration as indicated by immunohistochemistry, protein, and RNA analyses. MCP-1 was the most abundant chemokine, MIP-1α was the least abundant, and RANTES levels were intermediate. Mice treated with MCP-1, MIP-1α, and RANTES neutralizing antibodies had a significant decrease in Stx2 plus LPS-induced macrophage accumulation in the kidney, indicating that these chemokines are required for macrophage recruitment. Furthermore, mice exposed to these three neutralizing antibodies had decreased fibrin deposition in their kidneys, implying that macrophages contribute to the renal damage associated with HUS.
An Unusual Response Regulator Influences Sporulation at Early and Late Stages inStreptomyces coelicolor
Authors: Tian Yuqing , Fowler Kay , Findlay Kim , Tan Huarong , Chater Keith F.
Published: January 2007

WhiI, a regulator required for efficient sporulation septation in the aerial mycelium ofStreptomyces coelicolor, resembles response regulators of bacterial two-component systems but lacks some conserved features of typical phosphorylation pockets. Four amino acids of the abnormal “phosphorylation pocket” were changed by site-directed mutagenesis. UnlikewhiInull mutations, these point mutations did not interfere with sporulation septation but had various effects on spore maturation. Transcriptome analysis was used to compare gene expression in the wild-type strain, a D27A mutant (pale gray spores), a D69E mutant (wild-type spores), and a null mutant (white aerial mycelium, no spores) (a new variant of PCR targeting was used to introduce the point mutations into the chromosomal copy ofwhiI). The results revealed 45 genes that were affected by the deletion ofwhiI.Many of these showed increased expression in the wild type at the time when aerial growth and development were taking place. About half of them showed reduced expression in the null mutant, and about half showed increased expression. Some, but not all, of these 45 genes were also affected by the D27A mutation, and a few were affected by the D69E mutation. The results were consistent with a model in which WhiI acts differently at sequential stages of development. Consideration of the functions ofwhiI-influenced genes provides some insights into the physiology of aerial hyphae. Mutation of sevenwhiI-influenced genes revealed that three of them play roles in spore maturation.
A Single Residue Change in
Vibrio harveyi
Hemolysin Results in the Loss of Phospholipase and Hemolytic Activities and Pathogenicity for Turbot (
Scophthalmus maximus
)
Authors: Sun Boguang , Zhang Xiao-Hua , Tang Xuexi , Wang Shushan , Zhong Yingbin , Chen Jixiang , Austin Brian
Published: January 2007

Vibrio harveyi
hemolysin, an important virulence determinant in fish pathogenesis, was further characterized, and the enzyme was identified as a phospholipase B by gas chromatography. Site-directed mutagenesis revealed that a specific residue, Ser153, was critical for its enzymatic activity and for its virulence in fish.
A Novel Two-Component Signaling System That Activates Transcription of an Enterohemorrhagic
Escherichia coli
Effector Involved in Remodeling of Host Actin
Authors: Reading Nicola C. , Torres Alfredo G. , Kendall Melissa M. , Hughes David T. , Yamamoto Kaneyoshi , Sperandio Vanessa
Published: January 2007

Enterohemorrhagic
Escherichia coli
(EHEC) O157:H7 is responsible for worldwide outbreaks of bloody diarrhea, hemorrhagic colitis, and life-threatening hemolytic uremic syndrome. After colonizing the large intestine, EHEC forms attaching and effacing (AE) lesions on intestinal epithelial cells. These lesions cause destruction of the microvilli and elicit actin rearrangement to form pedestals that cup each bacterium individually. EHEC responds to a signal produced by the intestinal microbial flora, autoinducer-3 (AI-3), and the host hormones epinephrine and norepinephrine to activate transcription of the genes involved in AE lesion formation. These three signals, involved in interkingdom communication, are sensed by bacterial sensor kinases. Here we describe a novel two-component system, QseEF (
q
uorum-
s
ensing
E. coli
regulators E and F), which is part of the AI-3/epinephrine/norepinephrine signaling system. QseE is the sensor kinase and QseF the response regulator. The
qseEF
genes are cotranscribed, and transcription of
qseEF
is activated by epinephrine through the QseC sensor. A
qseF
mutant does not form AE lesions. QseF activates transcription of the gene encoding EspFu, an effector protein translocated to the host cell by the EHEC, which mimics a eukaryotic SH2/SH3 adapter protein to engender actin polymerization during pedestal formation. Expression of the
espFu
gene from a plasmid restored AE lesion formation to the
qseF
mutant, suggesting that lack of
espFu
expression in this mutant was responsible for the loss of pedestal formation. These findings suggest the QseEF is a two-component system involved in the regulation of AE lesion formation by EHEC.
Management of septic arthritis: a systematic review
Authors: Mathews C J , Kingsley G , Field M , Jones A , Weston V C , Phillips M , Walker D , Coakley G
Published: January 2007

Objective

To evaluate the existing evidence on the diagnosis and management of septic arthritis in native joints.

Design

Systematic review.

Data sources

Cochrane Library, Medline, Embase, National Electronic Library for Health, reference lists, national experts.

Review methods

Systematic review of the literature with evaluation of the methodological quality of the selected papers using defined criteria set out by the Clinical Effectiveness and Evaluation Unit of the Royal College of Physicians.

Results

3291 citations were initially identified. Of these, 189 full text articles were identified for potential selection. Following review of these full text articles, 80 articles were found to fulfil the inclusion criteria and were included in the final list. Conclusions were drawn on the diagnosis, investigation and management of septic arthritis.

Discussion

Little good quality evidence exists to guide the diagnosis and management of septic arthritis. Overall, no investigation is more reliable in the diagnosis of septic arthritis than the opinion of an experienced doctor. Aspiration and culture of synovial fluid is crucial to the diagnosis, but measurement of cell count is unhelpful. Antibiotics are clearly required for a prolonged period, but there are no data to indicate by which route or for how long. Key unanswered questions remain surrounding the medical and surgical management of the infected joint.
Endoscopic ultrasound guided fine needle aspiration of non-pancreatic lesions: an institutional experience
Authors: Anand Dipti , Barroeta Julieta E , Gupta Prabodh K , Kochman Michael , Baloch Zubair W
Published: January 2007

Background:

Endoscopic ultrasound guided fine needle aspiration biopsy (EUS-FNA) has proven to be an effective diagnostic modality for the detection and staging of pancreatic malignancies. In recent years EUS-FNA has also been used to diagnose lesions of non-pancreatic sites such as structures in close proximity to the gut wall within the mediastinum, abdomen, pelvis and retro-peritoneum.

Aims:

To evaluate experience with EUS-FNA of non-pancreatic sites at a large university medical centre.

Methods:

The study cohort included 234 patients who underwent EUS-FNA of 246 lesions in non-pancreatic sites (122 peri-pancreatic and coeliac lymph nodes; 9 peri-pancreatic masses; other sites: mediastinum 12, gastric 25, liver 27, oesophagus 17, duodenum/colon/rectum 15, retro-peritoneum 8, lung 7, miscellaneous 4).

Results:

The cytology diagnoses were classified as non-neoplastic/reactive in 82 (33%), atypical/suspicious for malignancy in 25 (10%), malignant in 86 (35%) and non-diagnostic in 53 (22%) cases. Surgical pathology follow-up was available in 75 (31%) cases. Excluding the non-diagnostic cases there were 7 false negative and 3 false positive cases. The sensitivity, specificity and positive predictive value of EUS-FNA in the diagnosis of lesions of non-pancreatic sites was 92%, 98% and 97%, respectively.

Conclusions:

EUS-FNA can be effectively used as a diagnostic modality in the diagnosis of lesions from non-pancreatic sites.
Chemokine:Receptor Structure, Interactions, and Antagonism
Authors: Allen Samantha J. , Crown Susan E. , Handel Tracy M.
Published: January 2007

Chemokines are critical mediators of cell migration during routine immune surveillance, inflammation, and development. Chemokines bind to G protein–coupled receptors and cause conformational changes that trigger intracellular signaling pathways involved in cell movement and activation. Although chemokines evolved to benefit the host, inappropriate regulation or utilization of these proteins can contribute to or cause many diseases. Specific chemokine receptors provide the portals for HIV to get into cells, and others contribute to inflammatory diseases and cancer. Thus, there is significant interest in developing receptor antagonists. To this end, the structures of ligands coupled with mutagenesis studies have revealed mechanisms for antagonism based on modified proteins. Although little direct structural information is available on the receptors, binding of small molecules to mutant receptors has allowed the identification of key residues involved in the receptor-binding pockets. In this review, we discuss the current knowledge of chemokine:receptor structure and function, and its contribution to drug discovery.
T Cells as a Self-Referential, Sensory Organ
Authors: Davis Mark M. , Krogsgaard Michelle , Huse Morgan , Huppa Johannes , Lillemeier Bjoern F. , Li Qi-jing
Published: January 2007

In light of recent data showing that both helper and cytotoxic T cells can detect even a single molecule of an agonist peptide-MHC, αβ T cells are clearly a type of sensory cell, comparable to any in the nervous system. In addition, endogenous (self) peptides bound to MHCs are not just important for thymic selection, but also play an integral role in T cell activation in the response to foreign antigens. With the multitude of specificities available to most T cells, they can thus be considered as a sensory organ, trained on self-peptide-MHCs and primed to detect nonself.
Ontogeny of the Hematopoietic System
Authors: Cumano Ana , Godin Isabelle
Published: January 2007

Blood cells are constantly produced in the bone marrow (BM) of adult mammals. This constant turnover ultimately depends on a rare population of progenitors that displays self-renewal and multilineage differentiation potential, the hematopoietic stem cells (HSCs). It is generally accepted that HSCs are generated during embryonic development and sequentially colonize the fetal liver, the spleen, and finally the BM. Here we discuss the experimental evidence that argues for the extrinsic origin of HSCs and the potential locations where HSC generation might occur. The identification of the cellular components playing a role in the generation process, in these precise locations, will be important in understanding the molecular mechanisms involved in HSC production from undifferentiated mesoderm.
Cellular Responses to Viral Infection in Humans: Lessons from Epstein-Barr Virus
Authors: Hislop Andrew D. , Taylor Graham S. , Sauce Delphine , Rickinson Alan B.
Published: January 2007

Epstein-Barr virus (EBV) provides a useful model to study cellular immunity to a genetically stable, persistent human virus. Different sets of proteins expressed during EBV's lytic and cell transforming infections induce qualitatively different cellular immune responses. The factors governing immunodominance hierarchies and the biological effectiveness of these different responses are now being revealed. Analysis of infectious mononucleosis (IM), a clinical syndrome that can arise during primary EBV infection, has allowed the evolution of the responses to be tracked over time, giving an understanding of the immune response kinetics and of those determinants affecting selection into memory. Furthermore, following IM, expression of the receptor for the homeostatic cytokine IL-15 on NK and T cells is lost within these individuals. This experiment of nature provides a system to advance understanding of immunological homeostasis in humans, illustrating how data obtained from the study of EBV have wider significance to the immunological community.
IL-17 Family Cytokines and the Expanding Diversity of Effector T Cell Lineages
Authors: Weaver Casey T. , Hatton Robin D. , Mangan Paul R. , Harrington Laurie E.
Published: January 2007

Since its conception two decades ago, the Th1-Th2 paradigm has provided a framework for understanding T cell biology and the interplay of innate and adaptive immunity. Naive T cells differentiate into effector T cells with enhanced functional potential for orchestrating pathogen clearance largely under the guidance of cytokines produced by cells of the innate immune system that have been activated by recognition of those pathogens. This secondary education of post-thymic T cells provides a mechanism for appropriately matching adaptive immunity to frontline cues of the innate immune system. Owing in part to the rapid identification of novel cytokines of the IL-17 and IL-12 families using database searches, the factors that specify differentiation of a new effector T cell lineage—Th17—have now been identified, providing a new arm of adaptive immunity and presenting a unifying model that can explain many heretofore confusing aspects of immune regulation, immune pathogenesis, and host defense.
The Host Defense of Drosophila melanogaster
Authors: Lemaitre Bruno , Hoffmann Jules
Published: January 2007

To combat infection, the fruit fly Drosophila melanogaster relies on multiple innate defense reactions, many of which are shared with higher organisms. These reactions include the use of physical barriers together with local and systemic immune responses. First, epithelia, such as those beneath the cuticle, in the alimentary tract, and in tracheae, act both as a physical barrier and local defense against pathogens by producing antimicrobial peptides and reactive oxygen species. Second, specialized hemocytes participate in phagocytosis and encapsulation of foreign intruders in the hemolymph. Finally, the fat body, a functional equivalent of the mammalian liver, produces humoral response molecules including antimicrobial peptides. Here we review our current knowledge of the molecular mechanisms underlying Drosophila defense reactions together with strategies evolved by pathogens to evade them.
The Death Domain Superfamily in Intracellular Signaling of Apoptosis and Inflammation
Authors: Park Hyun Ho , Lo Yu-Chih , Lin Su-Chang , Wang Liwei , Yang Jin Kuk , Wu Hao
Published: January 2007

The death domain (DD) superfamily comprising the death domain (DD) subfamily, the death effector domain (DED) subfamily, the caspase recruitment domain (CARD) subfamily, and the pyrin domain (PYD) subfamily is one of the largest domain superfamilies. By mediating homotypic interactions within each domain subfamily, these proteins play important roles in the assembly and activation of apoptotic and inflammatory complexes. In this chapter, we review the molecular complexes assembled by these proteins, the structural and biochemical features of these domains, and the molecular interactions mediated by them. By analyzing the potential molecular basis for the function of these domains, we hope to provide a comprehensive understanding of the function, structure, interaction, and evolution of this important family of domains.
Effect of simultaneous intracoronary guidewires on the predictive accuracy of functional parameters of coronary lesion severity
Authors: Verberne Hein J. , Meuwissen Martijn , Chamuleau Steven A. J. , Verhoeff Bart-Jan , van Eck-Smit Berthe L. F. , Spaan Jos A. E. , Piek Jan J. , Siebes Maria
Published: January 2007

The aim of this study was to assess the influence of a second guidewire on the diagnostic accuracy of functional parameters of coronary lesion severity. Sixty-five patients with intermediate coronary lesions underwent myocardial perfusion scintigraphy. Fractional flow reserve (FFR), coronary flow velocity reserve (CFVR), and hyperemic stenosis resistance (HSR) index (HSR = stenosis pressure gradient ÷ velocity) were determined in 77 lesions. Distal pressure and velocity were acquired simultaneously (dual wire) and sequentially (single wire) with two sensor-equipped guidewires. Overall, functional parameters deteriorated from single- to dual-wire assessment. In patients without ischemia, the good diagnostic performance of FFR, CFVR, and HSR deteriorated significantly ( P < 0.001) when assessed by dual wires, with an increase in the number of false-positive results. This trend was more pronounced for HSR, since the presence of a second wire reduced maximal velocity and increased the pressure gradient. The presence of two guidewires, especially across a myocardial perfusion scintigraphy-induced nonsignificant lesion, is associated with overestimation of the hemodynamically assessed lesion severity and, therefore, is likely to have a major impact on clinical decision making. This underscores the advantage of a dual-sensor-equipped guidewire for the evaluation of stenosis severity by combined pressure and velocity measurements.
Frequency-dependent effects of variousIKrblockers on cardiac action potential duration in a human atrial model
Authors: Tsujimae Kenji , Suzuki Shingo , Murakami Shingo , Kurachi Yoshihisa
Published: January 2007

Rapidly activating K+current ( IKr) blockers prolong action potential (AP) duration (APD) in a reverse-frequency-dependent manner and may induce arrhythmias, including torsade de pointes in the ventricle. The IKrblocker dofetilide has been approved for treatment of atrial arrhythmias, including fibrillation. There are, however, a limited number of studies on the action of IKrblockers on atrial AP. When we tested a mathematical model of the human atrial AP (M Courtemanche, RJ Ramirez, S Nattel. Am J Physiol Heart Circ Physiol 275: H301–H321, 1998) to examine the effects of dofetilide-type IKrblockade, this model could not reproduce the reverse-frequency-dependent nature of IKrblockade on atrial APD. We modified the model by introducing a slowly activating K+current activation parameter. As the slow time constant was increased, dofetilide-type blockade induced more prominent reverse-frequency-dependent APD prolongation. Using the modified model, we also examined the effects of two more types of IKrblockade similar to those of quinidine and vesnarinone. Voltage- and time-dependent block of IKrthrough the onset of inhibition by quinidine is much faster than by vesnarinone. When we incorporated the kinetics of the effects of these drugs on IKrinto the model, we found that quinidine-type blockade caused a reverse-frequency-dependent prolongation of APD that was similar to the effect of dofetilide-type blockade, whereas vesnarinone-type blockade did not. This finding coincides with experimental observations. The lack of the reverse frequency dependence in vesnarinone-type blockade was accounted for by the slow development of IKrblockade at depolarized potentials. These results suggest that the voltage- and time-dependent nature of IKrblockade by drugs may be critical for the phenotype of the drug effect on atrial AP.
NADPH oxidase modulates myocardial Akt, ERK1/2 activation, and angiogenesis after hypoxia-reoxygenation
Authors: Chen Jian-Xiong , Zeng Heng , Tuo Qin-Hui , Yu Heidi , Meyrick Barbara , Aschner Judy L.
Published: January 2007

Recent studies have demonstrated that reactive oxygen species (ROS) mediate myocardial ischemia-reperfusion (I/R) and angiogenesis via the mitogen-activated protein kinases and the serine-threonine kinase Akt/protein kinase B pathways. NADPH oxidases are major sources of ROS in endothelial cells and cardiomyocytes. In the present study, we investigated the role of NADPH oxidase-derived ROS in hypoxia-reoxygenation (H/R)-induced Akt and ERK1/2 activation and angiogenesis using porcine coronary artery endothelial cells (PCAECs) and a mouse myocardial I/R model. Our data demonstrate that exposure of PCAECs to hypoxia for 2 h followed by 1 h of reoxygenation significantly increased ROS formation. Pretreatment with the NADPH oxidase inhibitors, diphenyleneiodonium (DPI, 10 μM) and apocynin (Apo, 200 and 600 μM), significantly attenuated H/R-induced ROS formation. Furthermore, exposure of PCAECs to H/R caused a significant increase in Akt and ERK1/2 activation. Exposure of PCAEC spheroids and mouse aortic rings to H/R significantly increased endothelial spheroid sprouting and vessel outgrowth, whereas pharmacological inhibition of NADPH oxidase or genetic deletion of the NADPH oxidase subunit, p47phox(p47phox−/−), significantly suppressed these changes. With the use of a mouse I/R model, our data further show that the increases in myocardial Akt and ERK1/2 activation and vascular endothelial growth factor (VEGF) expression were markedly blunted in the p47phox−/−mouse subjected to myocardial I/R compared with the wild-type mouse. Our findings underscore the important role of NADPH oxidase and its subunit p47phoxin modulating Akt and ERK1/2 activation, angiogenic growth factor expression, and angiogenesis in myocardium undergoing I/R.