bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complement Receptor 3 and Toll-Like Receptor 4 Act Sequentially in Uptake and Intracellular Killing of UnopsonizedSalmonella entericaSerovar Typhimurium by Human Neutrophils
Authors: van Bruggen Robin , Zweers Debby , van Diepen Angela , van Dissel Jaap T. , Roos Dirk , Verhoeven Arthur J. , Kuijpers Taco W. 
Published: March 2007

ABSTRACTThe uptake and subsequent killing ofSalmonella entericaserovar Typhimurium by human neutrophils was studied. In particular, two pattern recognition receptors, complement receptor 3 (CR3) and Toll-like receptor 4 (TLR4), were found to be essential for the efficient uptake and activation, respectively, of the NADPH oxidase. The uptake ofSalmonellawas almost completely inhibited by various monoclonal antibodies against CR3, and neutrophils from a patient with leukocyte adhesion deficiency type 1, which lack CR3, showed almost no uptake ofSalmonella. A lipopolysaccharide (LPS) mutant strain ofSalmonellawas used to show that the expression of full-length, wild-type, or so-called smooth LPS is important for the efficient killing of intracellularSalmonella. Infection with wild-type-LPS-expressingSalmonellaresulted in the generation of reactive oxygen species (ROS) in TLR4-decorated,Salmonella-containing vacuoles, whereas ROS were not induced by an LPS mutant strain. In addition, the recognition ofSalmonellaby neutrophils, leading to ROS production, was shown to be intracellular, as determined by priming experiments with intact bacteria under conditions where the bacterium is not taken up. Finally, the generation of ROS in the wild-type-Salmonella-infected neutrophils was largely inhibited by the action of a TLR4-blocking, cell-permeable peptide, showing that signaling by this receptor from theSalmonella-containing vacuole is essential for the activation of the NADPH oxidase. In sum, our data identify the sequential recognition of unopsonizedSalmonellastrains by CR3 and TLR4 as essential events in the efficient uptake and killing of this intracellular pathogen.
Murine Aerosol Challenge Model of Anthrax
Authors: Loving Crystal L. , Kennett Mary , Lee Gloria M. , Grippe Vanessa K. , Merkel Tod J. 
Published: March 2007

ABSTRACTThe availability of relevant and useful animal models is critical for progress in the development of effective vaccines and therapeutics. The infection of rabbits and non-human primates with fully virulentBacillus anthracisspores provides two excellent models of anthrax disease. However, the high cost of procuring and housing these animals and the specialized facilities required to deliver fully virulent spores limit their practical use in early stages of product development. Conversely, the small size and low cost associated with using mice makes this animal model more practical for conducting experiments in which large numbers of animals are required. In addition, the availability of knockout strains and well-characterized immunological reagents makes it possible to perform studies in mice that cannot be performed easily in other species. Although we, along with others, have used the mouse aerosol challenge model to examine the outcome ofB. anthracisinfection, a detailed characterization of the disease is lacking. The current study utilizes a murine aerosol challenge model to investigate disease progression, innate cytokine responses, and histological changes during the course of anthrax after challenge with aerosolized spores. Our results show that anthrax disease progression in a complement-deficient mouse after challenge with aerosolized Sterne spores is similar to that described for other species, including rabbits and non-human primates, challenged with fully virulentB. anthracis. Thus, the murine aerosol challenge model is both useful and relevant and provides a means to further investigate the host response and mechanisms ofB. anthracispathogenesis.
Integrated Response to Inducers by Communication between a Catabolic Pathway and Its Regulatory System
Authors: Martínez-Pérez Olga , López-Sánchez Aroa , Reyes-Ramírez Francisca , Floriano Belén , Santero Eduardo 
Published: March 2007

ABSTRACT
Efficient gene regulation of metabolic pathways implies that the profile of molecules inducing the pathway matches that of the molecules that are metabolized. Gratuitous induction, a well-known phenomenon in catabolic pathways, is the consequence of differences in the substrate and inducer profiles. This phenomenon is particularly evident in pathways for biodegradation of organic contaminants that can be induced by a variety of molecules similar to the real substrates. Analysis of the regulation of tetralin biodegradation genes in mutant strains with mutations that affect each component of the initial dioxygenase enzymatic complex indicated that the response of the regulatory system to potential inducers is altered differently depending on the mutated component. Based on the expression phenotypes of a number of single or double mutants, we propose a model that represents an unprecedented way of communication between a catabolic pathway and its regulatory system to prevent efficient induction by a molecule that is not a real substrate. This communication allows a better fit of the substrate and inducer profiles, thus minimizing gratuitous induction, without a requirement for optimal coevolution to match the specificity of catabolic enzymes and their regulatory systems. Modulation of the regulatory system in this way not only provides a more appropriate response to potential inducers recognized by the regulatory system but also may properly adjust the levels of gene expression to the substrate availability.
Degradation of Alkyl Methyl Ketones by
Pseudomonas veronii
MEK700
Authors: Onaca Christina , Kieninger Martin , Engesser Karl-H. , Altenbuchner Josef 
Published: March 2007

ABSTRACT

Pseudomonas veronii
MEK700 was isolated from a biotrickling filter cleaning 2-butanone-loaded waste air. The strain is able to grow on 2-butanone and 2-hexanol. The genes for degradation of short chain alkyl methyl ketones were identified by transposon mutagenesis using a newly designed transposon, mini-Tn
5495
, and cloned in
Escherichia coli
. DNA sequence analysis of a 15-kb fragment revealed three genes involved in methyl ketone degradation. The deduced amino acid sequence of the first gene,
mekA
, had high similarity to Baeyer-Villiger monooxygenases; the protein of the second gene,
mekB
, had similarity to homoserine acetyltransferases; the third gene,
mekR
, encoded a putative transcriptional activator of the AraC/XylS family. The three genes were located between two gene groups: one comprising a putative phosphoenolpyruvate synthase and glycogen synthase, and the other eight genes for the subunits of an ATPase. Inactivation of
mekA
and
mekB
by insertion of the mini-transposon abolished growth of
P. veronii
MEK700 on 2-butanone and 2-hexanol. The involvement of
mekR
in methyl ketone degradation was observed by heterologous expression of
mekA
and
mekB
in
Pseudomonas putida
. A fragment containing
mekA
and
mekB
on a plasmid was not sufficient to allow
P. putida
KT2440 to grow on 2-butanone. Not until all three genes were assembled in the recombinant
P. putida
was it able to use 2-butanone as carbon source. The Baeyer-Villiger monooxygenase activity of MekA was clearly demonstrated by incubating a
mekB
transposon insertion mutant of
P. veronii
with 2-butanone. Hereby, ethyl acetate was accumulated. To our knowledge, this is the first time that ethyl acetate by gas chromatographic analysis has been definitely demonstrated to be an intermediate of MEK degradation. The
mekB
-encoded protein was heterologously expressed in
E. coli
and purified by immobilized metal affinity chromatography. The protein exhibited high esterase activity towards short chain esters like ethyl acetate and 4-nitrophenyl acetate.
Expression Analysis of Multiple
dnaK
Genes in the Cyanobacterium
Synechococcus elongatus
PCC 7942
Authors: Sato Masumi , Nimura-Matsune Kaori , Watanabe Satoru , Chibazakura Taku , Yoshikawa Hirofumi 
Published: March 2007

ABSTRACT

We analyzed the stress responses of three
dnaK
homologues (
dnaK1
,
dnaK2
, and
dnaK3
) in the cyanobacterium
Synechococcus elongatus
PCC 7942. A reporter assay showed that under stress conditions the expression of only the
dnaK2
gene was induced, suggesting a functional assignment of these homologues. RNA blot hybridization indicated a typical stress response of
dnaK2
to heat and high-light stress. Primer extension mapping showed that
dnaK2
was transcribed from similar sites under various stress conditions. Although no known sequence motif was detected in the upstream region, a 20-bp sequence element was highly conserved in
dnaK2
; it was essential not only for the stress induction but also for the basal expression of
dnaK2
. The ubiquitous upstream localization of this element in each heat shock gene suggests its important role in the cyanobacterial stress response.
Defining Genomic Islands and Uropathogen-Specific Genes in Uropathogenic
Escherichia coli
Authors: Lloyd Amanda L. , Rasko David A. , Mobley Harry L. T. 
Published: March 2007

ABSTRACT

Uropathogenic
Escherichia coli
(UPEC) strains are responsible for the majority of uncomplicated urinary tract infections, which can present clinically as cystitis or pyelonephritis. UPEC strain CFT073, isolated from the blood of a patient with acute pyelonephritis, was most cytotoxic and most virulent in mice among our strain collection. Based on the genome sequence of CFT073, microarrays were utilized in comparative genomic hybridization (CGH) analysis of a panel of uropathogenic and fecal/commensal
E. coli
isolates. Genomic DNA from seven UPEC (three pyelonephritis and four cystitis) isolates and three fecal/commensal strains, including K-12 MG1655, was hybridized to the CFT073 microarray. The CFT073 genome contains 5,379 genes; CGH analysis revealed that 2,820 (52.4%) of these genes were common to all 11
E. coli
strains, yet only 173 UPEC-specific genes were found by CGH to be present in all UPEC strains but in none of the fecal/commensal strains. When the sequences of three additional sequenced UPEC strains (UTI89, 536, and F11) and a commensal strain (HS) were added to the analysis, 131 genes present in all UPEC strains but in no fecal/commensal strains were identified. Seven previously unrecognized genomic islands (>30 kb) were delineated by CGH in addition to the three known pathogenicity islands. These genomic islands comprise 672 kb of the 5,231-kb (12.8%) genome, demonstrating the importance of horizontal transfer for UPEC and the mosaic structure of the genome. UPEC strains contain a greater number of iron acquisition systems than do fecal/commensal strains, which is reflective of the adaptation to the iron-limiting urinary tract environment. Each strain displayed distinct differences in the number and type of known virulence factors. The large number of hypothetical genes in the CFT073 genome, especially those shown to be UPEC specific, strongly suggests that many urovirulence factors remain uncharacterized.
Error-Prone DNA Repair System in EnteroaggregativeEscherichia coliIdentified by Subtractive Hybridization
Authors: Joo Lucy M. , Macfarlane-Smith Louissa R. , Okeke Iruka N. 
Published: March 2007

ABSTRACTEnteroaggregativeEscherichia coli(EAEC) are etiologic agents of diarrhea. The EAEC category is heterogeneous, but most in-depth experimentation has focused on prototypical strain, 042. We hypothesized that 60A, another EAEC strain, might posses virulence or fitness genes that 042 does not have. Through subtractive hybridization we identified 60A-specific sequences, including loci present in otherE. coliand phage DNA. One locus thus identified wasimpB, a LexA repressed error-prone DNA repair gene that has been identified in plasmids from other enteric organisms and which we detected in 21 of 34 EAEC strains. An isogenic 60AimpBmutant showed decreased survival and mutagenesis after exposure to UV, as well as bile salt exposure, compared to the wild-type strain, and these phenotypes could be complemented in trans. The EAEC strain 60Aimpoperon differs structurally from previously described homologs. A cryptic gene,impC, present in otherimpoperons, is absent from 60A. In addition, transcription ofimpABin strain 60A occurs from a promoter that is dissimilar to the previously describedimpCpromoter but is still triggered by UV-mediated damage. In strain 60A theimpABand the aggregative adherence fimbriae I (AAF/I)-encoding genes are on the same large plasmid, and the 60A version of the operon is predominantly seen in AAF/I-positive EAEC. SupplementaryimpSOS-inducible error-prone repair systems are common among EAEC even though they are absent in prototypical strain 042.
TraY and Integration Host Factor
oriT
Binding Sites and F Conjugal Transfer: Sequence Variations, but Not Altered Spacing, Are Tolerated
Authors: Williams Sarah L. , Schildbach Joel F. 
Published: March 2007

ABSTRACT

Bacterial conjugation is the process by which a single strand of a conjugative plasmid is transferred from donor to recipient. For F plasmid, TraI, a relaxase or nickase, binds a single plasmid DNA strand at its specific origin of transfer (
oriT
) binding site,
sbi
, and cleaves at a site called
nic
. In vitro studies suggest TraI is recruited to
sbi
by its accessory proteins, TraY and integration host factor (IHF). TraY and IHF bind conserved
oriT
sites
sbyA
and
ihfA
, respectively, and bend DNA. The resulting conformational changes may propagate to
nic
, generating the single-stranded region that TraI can bind. Previous deletion studies performed by others showed transfer efficiency of a plasmid containing F
oriT
decreased progressively as increasingly longer segments, ultimately containing both
sbyA
and
ihfA
, were deleted. Here we describe our efforts to more precisely define the role of
sbyA
and
ihfA
by examining the effects of multiple base substitutions at
sbyA
and
ihfA
on binding and plasmid mobilization. While we observed significant decreases in in vitro DNA-binding affinities, we saw little effect on plasmid mobilization even when
sbyA
and
ihfA
variants were combined. In contrast, when half or full helical turns were inserted between the relaxosome protein-binding sites, mobilization was dramatically reduced, in some cases below the detectable limit of the assay. These results are consistent with TraY and IHF recognizing
sbyA
and
ihfA
with limited sequence specificity and with relaxosome proteins requiring proper spacing and orientation with respect to each other.
A Novel Fur- and Iron-Regulated Small RNA, NrrF, Is Required for Indirect Fur-Mediated Regulation of the
sdhA
and
sdhC
Genes in
Neisseria meningitidis
Authors: Mellin J. R. , Goswami Sulip , Grogan Susan , Tjaden Brian , Genco Caroline A. 
Published: March 2007

ABSTRACT

Iron is both essential for bacterial growth and toxic at higher concentrations; thus, iron homeostasis is tightly regulated. In
Neisseria meningitidis
the majority of iron-responsive gene regulation is mediated by the ferric uptake regulator protein (Fur), a protein classically defined as a transcriptional repressor. Recently, however, microarray studies have identified a number of genes in
N. meningitidis
that are iron and Fur activated, demonstrating a new role for Fur as a transcriptional activator. Since Fur has been shown to indirectly activate gene transcription through the repression of small regulatory RNA molecules in other organisms, we hypothesized that a similar mechanism could account for Fur-dependent, iron-activated gene transcription in
N. meningitidis
. In this study, we used a bioinformatics approach to screen for the presence of Fur-regulated small RNA molecules in
N. meningitidis
MC58. This screen identified one small RNA, herein named NrrF (for neisserial regulatory RNA responsive to iron [Fe]), which was demonstrated to be both iron responsive and Fur regulated and which has a well-conserved orthologue in
N. gonorrhoeae
. In addition, this screen identified a number of other likely, novel small RNA transcripts. Lastly, we utilized a new bioinformatics approach to predict regulatory targets of the NrrF small RNA. This analysis led to the identification of the
sdhA
and
sdhC
genes, which were subsequently demonstrated to be under NrrF regulation in an
nrrF
mutant. This study is the first report of small RNAs in
N. meningitidis
and the first to use a bioinformatics approach to identify, a priori, regulatory targets of a small RNA.
Arthroscopic Treatment of the Painful “Internal” Snapping Hip
Authors: Flanum Mark E. , Keene James S. , Blankenbaker Donna G. , DeSmet Arthur A. 
Published: March 2007

Background Traditional surgical treatment for a painful snapping iliopsoas tendon has been an open lengthening of the tendon. Hypothesis An endoscopic release will alleviate painful snapping of the tendon. Study Design Case series; Level of evidence, 4. Methods Six patients with painful snapping hips who had no pain relief after magnetic resonance arthrography, which included injection of bupivacaine into the hip joint, subsequently had an ultrasound evaluation of their iliopsoas tendons and an anesthetic injection into the psoas bursa. In all 6 patients, the injection relieved their hip pain, and in 4, real-time imaging demonstrated snapping of the tendon. All hips were evaluated with the 100-point Harris hip scoring system before and at 1.5, 3, 6, and 12 months after surgery. Results Preoperative hip scores averaged 58 points. After surgery, all patients had hip flexor weakness, used crutches for 5 weeks, and had 6-week scores that averaged 62 points. The patients continued to improve, and at 6 and 12 months, their scores averaged 90 and 96 points, respectively, and none had recurrence of their snapping or pain. Conclusion Ultrasound-guided anesthetic injection of the psoas bursa is useful to confirm snapping of the iliopsoas tendon as the cause of a patient's hip pain. Endoscopic release of the tendon is a safe outpatient procedure that provides effective relief of the snapping and pain.
In Vivo Measurement of the Pivot-Shift Test in the Anterior Cruciate Ligament—Deficient Knee Using an Electromagnetic Device
Authors: Hoshino Yuichi , Kuroda Ryosuke , Nagamune Kouki , Yagi Masayoshi , Mizuno Kiyonori , Yamaguchi Motoi , Muratsu Hirotsugu , Yoshiya Shinichi , Kurosaka Masahiro 
Published: March 2007

Background The pivot-shift test is commonly used for assessing dynamic instability in anterior cruciate ligament—insufficient knees, which is related to subjective knee function, unlike static load-displacement measurement. Conventional measurements of 3-dimensional position displacement cannot assess such dynamic instability in vivo and produce comparable parameters. Not only 3-dimensional position displacement but also its 3-dimensional acceleration should be measured for quantitative evaluation of the pivot-shift test. Hypothesis Knees with a positive pivot-shift test result have increased tibial anterior translation and acceleration of its subsequent posterior translation, and they are correlated with clinical grading. Study Design Controlled laboratory study. Materials and Methods Thirty patients with isolated anterior cruciate ligament injury were included. Pivot-shift tests were evaluated under anesthesia manually and experimentally using an electromagnetic knee 6 degrees of freedom measurement system. From 60 Hz of 6 degrees of freedom data, coupled tibial anterior translation was calculated, and acceleration of posterior translation was computed by secondary derivative. Results All anterior cruciate ligament—deficient knees demonstrated a positive pivot-shift test result. The coupled tibial anterior translation was 7.7 and 15.6 mm in anterior cruciate ligament—intact and —deficient knees, respectively. The acceleration of posterior translation was —797 and —2001 mm/s 2, respectively. These differences were significant (P < .01). The coupled tibial anterior translation and acceleration of posterior translation in the anterior cruciate ligament—deficient knee were larger in correlation with clinical grading (P = .03 and P < .01, respectively). Conclusion The increase of tibial anterior translation and acceleration of subsequent posterior translation could be detected in knees with a positive pivot-shift result, and this increase was correlated to clinical grading. Clinical Relevance These measurements can be used for quantified evaluation of dynamic instability demonstrated by the pivot-shift test.
Management of Morel-Lavallee Lesion of the Knee
Authors: Tejwani Samir G. , Cohen Steven B. , Bradley James P. 
Published: March 2007

Background The Morel-Lavallee lesion is a closed degloving injury most commonly described in the region of the hip joint after blunt trauma. It also occurs in the knee as a result of shearing trauma during football and is a distinct lesion from prepatellar bursitis and quadriceps contusion. Purpose To review the authors’ experience with Morel-Lavallee lesion of the knee in the elite contact athlete to construct a diagnostic and treatment algorithm. Study Design Case series; Level of evidence, 4. Methods Twenty-seven knees in 24 players were identified from 1 National Football League team's annual injury database as having sustained a Morel-Lavallee lesion between 1993 and 2006. Their charts were retrospectively reviewed. Results The most common mechanism of injury was a shearing blow on the playing surface (81%). The most common motion deficit was active flexion (41%). The mean time for resolution of the fluid collection and achievement of full active flexion was 16.3 days. The mean number of practices missed was 1.5. The mean number of games missed was 0.1. Fourteen knees (52%) were treated successfully with compression wrap, cryotherapy, and motion exercises. Thirteen knees (48%) were treated with at least 1 aspiration, and 6 knees (22%) were treated with multiple aspirations for recurrent serosanguineous fluid collections. In 3 cases (11%), the Morel-Lavallee lesion was successfully treated with doxycycline sclerodesis after 3 aspirations failed to resolve the recurrent fluid collections; return to play was immediate thereafter in each case. Conclusion In football, Morel-Lavallee lesion of the knee usually occurs from a shearing blow from the playing field. Diagnosis is confirmed when examination reveals a large suprapatellar area of palpable fluctuance. Elite athletes are typically able to return to practice and game play long before complete resolution of the lesion. Recurrent fluid collections can occur, necessitating aspiration in approximately half the cases for successful treatment. Recalcitrant fluid collections can be safely and expeditiously treated with doxycycline sclerodesis.