bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcription of Quorum-Sensing System Genes inClinical and Environmental Isolates of
Pseudomonasaeruginosa
Authors: Cabrol Ségolène , Olliver Anne , Pier Gerald B. , Andremont Antoine , Ruimy Raymond 
Published: December 2003

ABSTRACT

Quorum
sensing (QS)-based transcriptional responses in
Pseudomonas
aeruginosa
have been defined on the basis of increases in
transcript levels of QS-controlled genes such as
lasB
and
aprA
following the hierarchical transcriptional increases of
central controllers such as the
lasR
gene. These
increases occur at high bacterial concentrations such as
early-stationary-phase growth in vitro. However, the extent to which
the increases occur in a variety of clinical and environmental isolates
has not been determined nor is there extensive information on allelic
variation in
lasR
genes. An analysis of the sequences of the
lasR
gene among 66 clinical and environmental isolates showed
that 81% have a sequence either identical to that of strain PAO1
or with a silent mutation, 15% have nucleotide changes resulting
in amino acid changes, and 5% have an insertion sequence in the
lasR
gene. Using real-time PCR to quantify transcript levels
of
lasR
,
lasB
, and
aprA
in the early log and
early stationary phases among 35 isolates from bacteremia and pneumonia
cases and the environment, we found most (33 of 35) strains had
increases in
lasR
transcripts in early stationary phase but
with a very wide range of final transcript levels per cell. There was a
strong correlation (
r
2
= 0.84) between
early-log- and early-stationary-phase transcript levels in all strains,
but this finding remained true only for the 50% of strains above
the median level of
lasR
found in early log phase. There were
significant (
P
< 0.05) but weak-to-modest correlations
of
lasR
transcript levels with
aprA
(r
2
=
0.2) and
lasB
(
r
2
= 0.5)
transcript levels, but again this correlation occurred only in the
50% of
P. aeruginosa
strains with the highest levels of
lasR
transcripts in early stationary phase. There were no
differences in distribution of
lasR
alleles among the
bacteremia, pneumonia, or environmental isolates. Overall, only about
50% of
P. aeruginosa
strains from clinical and
environmental sources show a
lasR
-dependent increase in the
transcription of
aprA
and
lasB
genes, indicating that
for about 50% of clinical isolates this regulatory system may
not play a significant role in
pathogenesis.
Novel Type of Specialized Transduction forCTXφ or Its Satellite Phage RS1 Mediated by Filamentous PhageVGJφ in
Vibriocholerae
Authors: Campos Javier , Martínez Eriel , Marrero Karen , Silva Yussuan , Rodríguez Boris L. , Suzarte Edith , Ledón Talena , Fando Rafael 
Published: December 2003

ABSTRACT

The
main virulence factor of
Vibrio cholerae
, the cholera toxin,
is encoded by the
ctxAB
operon, which is contained in the
genome of the lysogenic filamentous phage CTXφ. This phage
transmits
ctxAB
genes between
V. cholerae
bacterial
populations that express toxin-coregulated pilus (TCP), the
CTXφ receptor. In investigating new forms of
ctxAB
transmission, we found that
V. cholerae
filamentous phage
VGJφ, which uses the mannose-sensitive hemagglutinin (MSHA)
pilus as a receptor, transmits CTXφ or its satellite phage RS1
by an efficient and highly specific TCP-independent mechanism. This is
a novel type of specialized transduction consisting in the
site-specific cointegration of VGJφ and CTXφ (or RS1)
replicative forms to produce a single hybrid molecule, which generates
a single-stranded DNA hybrid genome that is packaged into hybrid viral
particles designated HybPφ (for the VGJφ/CTXφ
hybrid) and HybRSφ (for the VGJφ/RS1 hybrid). The
hybrid phages replicate by using the VGJφ replicating functions
and use the VGJφ capsid, retaining the ability to infect via
MSHA. The hybrid phages infect most tested strains more efficiently
than CTXφ, even under in vitro optimal conditions for TCP
expression. Infection and lysogenization with HybPφ revert the
V. cholerae
live attenuated vaccine strain 1333 to virulence.
Our results reinforce that TCP is not indispensable for the acquisition
of CTXφ. Thus, we discuss an alternative to the current
accepted evolutionary model for the emergence of new toxigenic strains
of
V. cholerae
and the importance of our findings for the
development of an environmentally safer live attenuated cholera
vaccine.
Horizontal Transfer of Segments of the 16S rRNA Genesbetween Species of the
Streptococcus anginosus
Group
Authors: Schouls Leo M. , Schot Corrie S. , Jacobs Jan A. 
Published: December 2003

ABSTRACT

The
nature in variation of the 16S rRNA gene of members of the
Streptococcus anginosus
group was investigated by
hybridization and DNA sequencing. A collection of 708 strains was
analyzed by reverse line blot hybridization. This revealed the presence
of distinct reaction patterns representing 11 different hybridization
groups. The 16S rRNA genes of two strains of each hybridization group
were sequenced to near-completion, and the sequence data confirmed the
reverse line blot hybridization results. Closer inspection of the
sequences revealed mosaic-like structures, strongly suggesting
horizontal transfer of segments of the 16S rRNA gene between different
species belonging to the
Streptococcus anginosus
group.
Southern blot hybridization further showed that within a single strain
all copies of the 16S rRNA gene had the same composition, indicating
that the apparent mosaic structures were not PCR-induced artifacts.
These findings indicate that the highly conserved rRNA genes are also
subject to recombination and that these events may be fixed in the
population. Such recombination may lead to the construction of
incorrect phylogenetic trees based on the 16S rRNA
genes.
Controlof
Pseudomonas aeruginosa algZ
Expression bythe Alternative Sigma FactorAlgT
Authors: Wozniak Daniel J. , Sprinkle April B. , Baynham Patricia J. 
Published: December 2003

ABSTRACT

AlgZ
controls
Pseudomonas aeruginosa
alginate synthesis by
activating
algD
, yet
algZ
expression is not
detectable in nonmucoid strains. Mobility shift and Western blot assays
revealed that
algZ
expression requires the sigma factor AlgT.
The mapped
algZ
transcription start site revealed a consensus
AlgT-dependent promoter that, when mutated, substantially reduced
algZ
transcription.
Modulation of Factor V Levels in Plasma by Polymorphisms in the C2 Domain
Authors: Scanavini Daniela , Girelli Domenico , Lunghi Barbara , Martinelli Nicola , Legnani Cristina , Pinotti Mirko , Palareti Gualtiero , Bernardi Francesco 
Published: December 2003

Objective—Functional polymorphisms contributing to coagulation factor levels are preferential markers for association studies aimed at identifying prothrombic genetic components.Methods and Results—Factor V (FV) microsatellite genotypes were found to be associated with FV levels (P=0.003). Single nucleotide polymorphisms analysis and sequencing of the promoter and of coding regions identified two polymorphisms (Met2120Thr, Asp2194Gly) present in 20% of the population (n=1013) that are responsible for genotype-phenotype associations. The effect of the Met2120Thr polymorphism, both in plasma (mean reduction of FV level in the heterozygous condition: 25%) and in recombinant FV studies (34% reduction), was comparable to that of the Asp2194Gly change (20% and 34%, respectively). The study of 10 subjects with a rare genotype indicated that the Asp2194Gly substitution is the functional determinant of the reduced FV levels associated with the FVHR2 haplotype. Among Leiden carriers, the doubly heterozygous condition for FV2120Thr was found to be associated with a significantly increased activated protein-C resistance (APCR) (P<0.05), and the doubly heterozygous condition for FV2194Gly was found to be more frequent (P=0.009) in symptomatic than in asymptomatic subjects.Conclusions—Extensive analysis of FV polymorphisms indicated that changes in the C2 domain modulate FV levels and might increase APCR and thrombotic risk in FV Leiden carriers through a pseudohomozygous mechanism.
The plaque lipid lysophosphatidic acid stimulates platelet activation and platelet-monocyte aggregate formation in whole blood: involvement of P2Y1 and P2Y12 receptors
Authors: Haserück Nadine , Erl Wolfgang , Pandey Dharmendra , Tigyi Gabor , Ohlmann Philippe , Ravanat Catherine , Gachet Christian , Siess Wolfgang 
Published: December 2003

AbstractDespite the fact that lysophosphatidic acid (LPA) has been identified as a main platelet-activating lipid of mildly oxidized low-density lipoprotein (LDL) and human atherosclerotic lesions, it remains unknown whether it is capable of activating platelets in blood. We found that LPA at concentrations slightly above plasma levels induces platelet shape change, aggregation, and platelet-monocyte aggregate formation in blood. 1-alkyl-LPA (16:0 fatty acid) was almost 20-fold more potent than 1-acyl-LPA (16:0). LPA directly induced platelet shape change in blood and platelet-rich plasma obtained from all blood donors. However, LPA-stimulated platelet aggregation in blood was donor dependent. It could be completely blocked by apyrase and antagonists of the platelet adenosine diphosphate (ADP) receptors P2Y1 and P2Y12. These substances also inhibited LPA-induced aggregation of platelet-rich plasma and aggregation and serotonin secretion of washed platelets. These results indicate a central role for ADP-mediated P2Y1 and P2Y12 receptor activation in supporting LPA-induced platelet aggregation. Platelet aggregation and platelet-monocyte aggregate formation stimulated by LPA was insensitive to inhibition by aspirin. We conclude that LPA at concentrations approaching those found in vivo can induce platelet shape change, aggregation, and platelet-monocyte aggregate formation in whole blood and suggest that antagonists of platelet P2Y1 and P2Y12 receptors might be useful preventing LPA-elicited thrombus formation in patients with cardiovascular diseases.
Angiogenic switch during 5T2MM murine myeloma tumorigenesis: role of CD45 heterogeneity
Authors: Asosingh Kewal , De Raeve Hendrik , Menu Eline , Van Riet Ivan , Van Marck Eric , Van Camp Benjamin , Vanderkerken Karin 
Published: December 2003

AbstractThe active role of angiogenesis during disease progression is well recognized in solid tumors. In hematologic malignancies such as multiple myeloma (MM), it is not known whether tumor neovascularization is an epiphenomenon or whether it is actively involved in disease progression. At clinical presentation, myeloma disease and the associated angiogenesis are both well established. Here the 5T2MM murine model was used to analyze angiogenesis during preclinical myeloma stages. Bone marrow (BM) of 5T2MM-inoculated mice was analyzed at weekly intervals until the end stage of the disease. Histologic analysis and assessment of microvessel density (MVD) by CD31 staining demonstrated a preangiogenic stage of small tumor aggregates followed by an angiogenic switch and subsequently an angiogenic stage of progressive tumor growth and large, confluent tumor nodules. Flow cytometric analysis that indicated an increase in percentage CD45- MM cells preceded the angiogenic switch. Real-time polymerase chain reaction (RT-PCR) of sorted CD45+ and CD45- MM cells indicated higher vascular endothelial growth factor 120 (VEGF120) and VEGF164 transcripts in CD45- MM cells. VEGF enzyme-linked immunosorbent assay (ELISA) revealed high secretion by CD45- MM cells but no protein secretion by CD45+ MM cells, indicating angiogenic heterogeneity among the MM cells. These data suggest that, like in solid tumors, angiogenic switch and angiogenic heterogeneity exist in MM. (Blood. 2004;103:3131-3137)
Multiparameter analysis of murine bone marrow side population cells
Authors: Pearce Daniel J. , Ridler Christopher M. , Simpson Catherine , Bonnet Dominique 
Published: December 2003

AbstractWe describe the multiparameter flow cytometric analysis of the relationship between side population (SP) formation and well-characterized, antigen-defined stem cell subsets. We also compared the competitive repopulation ability of subsets defined by the SP profile to those identified by antigenic markers. The vast majority of SP cells possessed a primitive cell phenotype (c-kit+, SCA-1+, Thy-1+, CD31+, CD135neg, lineageneg), but only a minority of antigen-defined subsets were SP cells. Hence, although SP cells are identified independently of antigenic markers, they are not distinct from established stem cell phenotypes, but are a small subset of them. Approximately half of SP cells expressed CD34 at readily detectable levels, and one-third of SP cells possessed the primitive c-kit+, SCA-1+, lineageneg, CD34neg cell phenotype. Since most SP cells are a subset of c-kit+, Thy-1+, lineageneg, SCA-1+ cells (KTLS), we determined whether the SP cell subset represents a further enrichment in long-term repopulating cell content. The SP+ subset of KTLS+ cells was more enriched for competitive repopulation units than the SP- fraction of KTLS+ cells. Hence, the SP cell fraction highlights a subset of the long-term repopulating cells found within the already highly purified KTLS fraction.
Potent inhibition of human platelets by cGMP analogs independent of cGMP-dependent protein kinase
Authors: Gambaryan Stepan , Geiger Jörg , Schwarz Ulrike R. , Butt Elke , Begonja Antonija , Obergfell Achim , Walter Ulrich 
Published: December 2003

AbstractPlatelets play a key role in hemostasis through their ability to rapidly adhere to activated or injured endothelium, subendothelial matrix proteins, and other activated platelets. A strong equilibrium between activating and inhibiting processes is essential for normal platelet and vascular function, impairment of this equilibrium being associated with either thrombophilic or bleeding disorders. Both cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) have been established as crucial and synergistic intracellular messengers that mediate the effects of platelet inhibitors such as nitric oxide (NO) and prostacyclin (PG-I2). However, it was recently suggested that a rapid cGMP/cGMP-dependent protein kinase (cGK)–mediated extracellular signal-related kinase (ERK) phosphorylation promotes platelet activation. This hypothesis was examined here by evaluating established and proposed cGK activators/inhibitors with respect to their capacity to promote either platelet activation or inhibition. In particular, the regulatory role of cGK for ERK phosphorylation and thrombin-, thromboxane-, and VWF-induced platelet activation was investigated. The data obtained do not support the concept that cGK-mediated ERK phosphorylation promotes platelet activation but confirm the inhibitory role of cGK in platelet function. One explanation for these discrepancies is the novel finding that extracellular cGMP analogs potently and rapidly inhibit thrombin-, thromboxane-, and VWF-induced human platelet signaling and activation by a cGK-independent mechanism.
The impact of cytomegalovirus serostatus of donor and recipient before hematopoietic stem cell transplantation in the era of antiviral prophylaxis and preemptive therapy
Authors: Boeckh Michael , Nichols W. Garrett 
Published: December 2003

AbstractIn the current era of effective prophylactic and preemptive therapy, cytomegalovirus (CMV) is now a rare cause of early mortality after hematopoietic stem cell transplantation (HSCT). However, the ultimate goal of completely eliminating the impact of CMV on survival remains elusive. Although the direct effects of CMV (ie, CMV pneumonia) have been largely eliminated, several recent cohort studies show that CMV-seropositive transplant recipients and seronegative recipients of a positive graft appear to have a persistent mortality disadvantage when compared with seronegative recipients with a seronegative donor. Recipients of T-cell–depleted allografts and/or transplants from unrelated or HLA-mismatched donors seem to be predominantly affected. Reasons likely include both incomplete prevention of direct and indirect or immunomodulatory effects of CMV as well as consequences of drug toxicities. The effect of donor CMV serostatus on outcome remains controversial. Large multicenter cohort studies are needed to better define the subgroups of seropositive patients that may benefit from intensified prevention strategies and to define the impact of CMV donor serostatus in the era of high-resolution HLA matching. Prevention strategies may require targeting both the direct and indirect effects of CMV infection by immunologic or antiviral drug strategies.
Calcium-Sensing Receptor Induces Proliferation through p38 Mitogen-Activated Protein Kinase and Phosphatidylinositol 3-Kinase But Not Extracellularly Regulated Kinase in a Model of Humoral Hypercalcemia of Malignancy
Authors: Tfelt-Hansen J. , Chattopadhyay N. , Yano S. , Kanuparthi D. , Rooney P. , Schwarz P. , Brown E. M. 
Published: December 2003

AbstractUsing H-500 rat Leydig cancer cells as a model of humoral hypercalcemia of malignancy (HHM), we previously showed that high Ca2+ induces PTH-related peptide (PTHrP) secretion via the calcium-sensing receptor (CaR) and mitogen- and stress-activated kinases, e.g. MAPK kinase 1 (MEK1), p38 MAPK, and stress-activated protein kinase 1/c-Jun N-terminal kinase. Because cellular proliferation is a hallmark of malignancy, we studied the role of the CaR in regulating the proliferation of H-500 cells. Elevated Ca2+ has a mitogenic effect on these cells that is mediated by the CaR, because the calcimimetic NPS R-467 also induced proliferation. Inhibition of phosphatidylinositol 3-kinase (PI3K) and p38 MAPK but not MEK1 abolished the mitogenic effect. Activation of PI3K by elevated Ca2+ was documented by phosphorylation of its downstream kinase, protein kinase B. Because protein kinase B activation promotes cell survival, we speculated that elevated Ca2+ might protect H-500 cells against apoptosis. Using terminal uridine deoxynucleotidyl nick end labeling staining, we demonstrated that high Ca2+ (7.5 mm) and NPS R-467 indeed protect cells against apoptosis induced by serum withdrawal compared with low Ca2+ (0.5 mm). Because the CaR induces PTHrP secretion, it is possible that the mitogenic and antiapoptotic effects of elevated Ca2+ could be indirect and mediated via PTHrP. However, blocking the type 1 PTH receptor with PTH (7–34) peptide did not alter either high Ca2+-induced proliferation or protection against apoptosis. Taken together, our data show that activation of PI3K and p38 MAPK but not of MEK1/ERK by the CaR promotes proliferation of H-500 cells as well as affords protection against apoptosis. These effects are likely direct without the involvement of PTHrP in an autocrine mode.
The Orphan Nuclear Receptors NURR1 and NGFIB Regulate Adrenal Aldosterone Production
Authors: Bassett Mary H. , Suzuki Takashi , Sasano Hironobu , White Perrin C. , Rainey William E. 
Published: December 2003

AbstractAldosterone biosynthesis in the zona glomerulosa of the adrenal cortex is regulated by transcription of CYP11B2 (encoding aldosterone synthase). The effects of nerve growth factor-induced clone B (NGFIB) (NR4A1), Nur-related factor 1 (NURR1) (NR4A2), and steroidogenic factor-1 (SF-1) (NR5A1) on transcription of human CYP11B2 (hCYP11B2) and hCYP11B1 (11β-hydroxylase) were compared in human H295R adrenocortical cells. hCYP11B2 expression was increased by NGFIB and NURR1. Although hCYP11B1 was activated by SF-1, cotransfection with SF-1 inhibited activation of hCYP11B2 by NGFIB and NURR1. NGFIB and NURR1 transcript and protein levels were strongly induced by angiotensin (Ang) II, the major regulator of hCYP11B2 expression in vivo. Sequential deletion and mutagenesis of the hCYP11B2 promoter identified two functional NGFIB response elements (NBREs), one located at −766/−759 (NBRE-1) and the previously studied Ad5 element at −129/−114. EMSAs suggested that both elements bound NGFIB and NURR1. In human adrenals, NURR1 immunoreactivity was preferentially localized in the zona glomerulosa and to a lesser degree in the zona fasciculata, whereas NGFIB was detected in both zones. The calmodulin kinase inhibitor KN93 partially blocked K+-stimulated transcription of NGFIB and NURR1. KN93 partially inhibited the effect of Ang II on NURR1 mRNA levels but did not modify the effect on expression of NGFIB. Mutation of the NBRE-1, Ad5, and Ad1/cAMP response element (CRE) cis-elements reduced both basal and Ang II-induced levels of hCYP11B2, demonstrating that all three elements are important for maximal transcriptional activity. Our results suggest that NGFIB and NURR1 are key regulators of hCYP11B2 expression and may partially mediate the regulation of hCYP11B2 by Ang II.
Retinoic acid regulates a subset of Cdx1 function in vivo
Authors: Houle Martin , Sylvestre Jean-René , Lohnes David 
Published: December 2003

Hox gene products are key players in establishing positional identity along the anteroposterior (AP) axis. In vertebrates, gain or loss of Hox expression along the AP axis often leads to inappropriate morphogenesis, typically manifesting as homeotic transformations that affect the vertebrae and/or hindbrain. Various signalling pathways are known to impact on Hox expression,including the retinoid signalling pathway. Exogenous retinoic acid (RA),disruption of enzymes involved in maintaining normal embryonic RA distribution or mutation of the retinoid receptors (RARs and RXRs) can all impact on Hox expression with concomitant effects on AP patterning.Several Hox loci have well characterized RA response elements (RAREs),which have been shown to regulate functionally relevant Hox expression in the neurectoderm. A similar crucial function for any RARE in mesodermal Hox expression has, however, not been documented. The means by which RA regulates mesodermal Hox expression could therefore be either through an undocumented direct mechanism or through an intermediary; these mechanisms are not necessarily exclusive. In this regard, we have found that Cdx1 may serve as such an intermediary. Cdx1 encodes a homeobox transcription factor that is crucial for normal somitic expression of several Hox genes, and is regulated by retinoid signalling in vivo and in vitro likely through an atypical RARE in the proximal promoter. In order to more fully understand the relationship between retinoid signalling, Cdx1 expression and AP patterning, we have derived mice in which the RARE has been functionally inactivated. These RARE-null mutants exhibit reduced expression of Cdx1 at all stages examined, vertebral homeotic transformations and altered Hox gene expression which correlates with certain of the defects seen in Cdx1-null offspring. These findings are consistent with a pivotal role for retinoid signalling in governing a subset of expression of Cdx1 crucial for normal vertebral patterning.
Nichtlineare Modellbildung und Regelung für hydraulische Schwenkflügelmotoren (Nonlinear Modeling and Control of Hydraulic Rotary Vane Actuators)
Authors: Bröcker Markus 
Published: December 2003

Abstract
Für hydraulische Schwenkflügelmotoren liefert dieser Beitrag umfassende Untersuchungen zur Modellbildung sowie zu Systemeigenschaften und die Herleitung eines nichtlinearen Regelungskonzepts – der D-flachheitsbasierten Regelung. Schwenkflügelmotoren lassen sich alternativ zu den bislang üblichen Differentialzylindern an den Armen von Großmanipulatoren integrieren. Durch diese neuen Konstruktionen der Roboterarme ist es möglich, die ungünstige Umlenkkinematik einzusparen. Dieser Wunsch stellt höhere Anforderungen an den Antrieb, sodass eine präzise Modellbildung und eine qualitativ hochwertige Trajektorienregelung des Schwenkflügelwinkels unabdingbar ist. Die Modellbildung des rotatorischen Antriebs als analytisches System mit linear einwirkender Steuerung (ALS) und die Herleitung von einfacheren nichtlinearen Systemklassen sind Grundlage für die Untersuchungen auf Steuerbarkeit und Beobachtbarkeit. Der Nachweis der D-Flachheit des Schwenkflügelmotors und die in einer Simulationsstudie erprobte D-flachheitsbasierte Regelung zeigen das enorme Potential des Schwenkflügelmotors für praktische Anwendungen auf.