bluuebunny/crossref_metadata_2025_split huggingface dataset:
Increased iron absorption during autologous blood donation supported by recombinant human erythropoietin therapy
Authors: Bovy Christophe , Baudoux Etienne , Salmon Jean Pol , Beguin Yves 
Published: September 2006

BACKGROUND:  Recombinant human erythropoietin (rHuEPO) therapy improves the success of autologous blood (AB) donation programs before elective surgery. The aim of this study was to evaluate iron absorption during an AB donation program with or without rHuEPO.STUDY DESIGN AND METHODS:  Thirty‐two patients were randomly assigned among placebo (Group 1) or 300 (Group 2) or 600 UI per kg rHuEPO (Group 3) on the first, second, and third donation visits. All patients also received daily oral iron (200 mg Fe+).RESULTS:  The number of units collected in Group 3 was higher than in Group 1 (4.6 ± 0.5 vs. 3.6 ± 0.8 units; p < 0.01). Red blood cell (RBC) production increased in a rHuEPO dose–dependent manner. With rHuEPO, the RBC volume collected per unit presented a lower decrease with number of donated units than with placebo and was similar to that of homologous blood units. Storage iron did not influence the number of units collected, whereas circulating mobilizable iron was the limiting factor. Oral iron absorption increased in a rHuEPO dose–dependent manner (12‐fold with 600 UI/kg rHuEPO) and was proportional to erythropoietic activity.CONCLUSION:  rHuEPO does not only improve the number of AB units collected but also their quality. Storage iron cannot meet marrow iron requirements, but rHuEPO strongly increased oral iron absorption in a dose‐dependent fashion through stimulation of erythropoietic activity.
Association of Unexplained Infertility with Gonadotropin and Ovarian Antibodies
Authors: Shatavi Seerin V. , Llanes Brainard , Luborsky Judith L. 
Published: September 2006

Problem  To determine the prevalence and characteristics of gonadotropin autoantibodies (GAB) associated with unexplained infertility, and to assess the relationship between ovarian autoantibodies (OVAB) and GAB.Method of study  Ovarian antibodies and GABs in sera of patients with unexplained infertility (n = 53) and a comparison (population) group from a blood bank (n = 40) were detected by immunoassay. Patients with unexplained infertility had either no prior gonadotropin treatment (n = 15) or two or more gonadotropin cycles to induce ovulation (n = 38).Results  The GABs were detected in 67% of women with treatment, 27% of women without treatment and 8% of women in the population. The GABs recognized follicle stimulating hormone (FSH) and luteinizing hormone (LH) and their alpha and beta subunits and to a lesser extent thyroid stimulating hormone (TSH) and prolactin. There was no significant difference in OVAB prevalence between gonadotropin treated or untreated women while GABs were significantly more frequent in gonadotropin treated women (P ≤ 0.01).Conclusion  Gonadotropin antibodies may represent a separate marker of ovarian autoimmunity in unexplained infertility as they are correlated with OVAB and are present in patients not treated with gonadotropin. However, as a higher frequency of GAB is associated with gonadotropin treatment, patients with ovarian autoimmunity may tend to have an immune response to gonadotropins in addition to an endocrine response.
Power transfer in non-linear gravitational clustering and asymptotic universality
Authors: Padmanabhan T. , Ray Suryadeep 
Published: September 2006

Abstract
We study the non-linear gravitational clustering of collisionless particles in an expanding background using an integro-differential equation for the gravitational potential. In particular, we address the question of how the non-linear mode–mode coupling transfers power from one scale to another in the Fourier space if the initial power spectrum is sharply peaked at a given scale. We show that the dynamical equation allows self-similar evolution for the gravitational potential φk(t) in Fourier space of the form φk(t) = F(t)D(k) where the function F(t) satisfies a second-order non-linear differential equation. We analyse the relevant solutions of this equation, thereby determining the asymptotic time evolution of the gravitational potential and density contrast. The analysis suggests that both F(t) and D(k) have well-defined asymptotic forms indicating that the power transfer leads to a universal power spectrum at late times. The analytic results are compared with numerical simulations, showing good agreement over the range at which we could test them.
Spectropolarimetry of PKS 0040-005 and the orientation of broad
absorption line quasar
Authors: Brotherton M. S. , De Breuck C. , Schaefer J. J. 
Published: September 2006

Abstract
We have used the Very Large Telescope (VLT) to obtain spectropolarimetry of the radio-loud, double-lobed broad absorption line (BAL) quasar PKS 0040−005. We find that the optical continuum of PKS 0040−005 is intrinsically polarized at 0.7 per cent with an electric vector position angle nearly parallel to that of the large-scale radio axis. This result is naturally explained in terms of an equatorial scattering region seen at a small inclination, building a strong case that the BAL outflow is not equatorial. In conjunction with other recent results concerning BAL quasars, the era of simply characterizing these sources as ‘edge-on’ is over.
Detached shells as tracers of asymptotic giant branch–interstellar medium bow shocks
Authors: Wareing C. J. , Zijlstra Albert A. , Speck Angela K. , O'Brien T. J. , Ueta Toshiya , Elitzur M. , Gehrz R. D. , Herwig F. , Izumiura H. , Matsuura M. , Meixner M. , Stencel R. E. , Szczerba R. 
Published: September 2006

Abstract
New Spitzer imaging observations have revealed the structure around the Mira variable star R Hya to be a one-sided parabolic arc 100 arcsec to the west, stretching from north to south. We successfully model R Hya and its surroundings in terms of an interaction of the stellar wind from an asymptotic giant branch (AGB) star with the interstellar medium (ISM) the star moves through. Our three-dimensional hydrodynamic simulation reproduces the structure as a bow shock into the oncoming ISM. We propose this as another explanation of detached shells around such stars, which should be considered alongside current theories of internal origin. The simulation predicts the existence of a tail of ram-pressure-stripped AGB material stretching downstream. Indications for such a tail behind R Hya are seen in IRAS maps.
The central elliptical galaxy in fossil groups and formation of brightest cluster galaxies
Authors: Khosroshahi Habib G. , Ponman Trevor J. , Jones Laurence R. 
Published: September 2006

Abstract
We study the dominant central giant elliptical galaxies in ‘fossil groups’ using deep optical (R-band) and near-infrared (Ks-band) photometry. These galaxies are as luminous as the brightest cluster galaxies (BCGs), raising immediate interest in their link to the formation of BCGs and galaxy clusters. However, despite apparent similarities, the dominant fossil galaxies show non-boxy isophotes, in contrast to the most luminous BCGs. This study suggests that the structure of the brightest group galaxies produced in fossil groups are systematically different to the majority of BCGs. If the fossils do indeed form from the merger of major galaxies including late-types within a group, then their discy nature is consistent with the results of recent numerical simulations of semi-analytical models which suggest that gas rich mergers result in discy isophote ellipticals.
We show that fossils form a homogeneous population in which the velocity dispersion of the fossil group is tightly correlated with the luminosity of the dominant elliptical galaxy. This supports the scenario in which the giant elliptical galaxies in fossils can grow to the size and luminosity of BCGs in a group environment. However, the boxy structure of luminous BCGs indicate that they are either not formed as fossils, or have undergone later gas-free mergers within the cluster environment.
Pregnenolone sulphate and Zn2+ inhibit recombinant rat GABAA receptor through different channel property
Authors: Wang M.‐D. , Rahman M. , Zhu D. , Bäckström T. 
Published: September 2006

AbstractAims:  We compared the antagonistic effects of state‐dependent gamma‐aminobutyric acid A (GABAA) receptor blockers picrotoxin, Zn2+ and pregnenolone sulphate (PS) on GABA‐ and pentobarbital‐activated currents in recombinant rat GABAA receptors in Xenopus oocytes.Methods:  Experiments were performed with wild type ratα1β2γ2L and α1β2 receptors, mutants α1V256Sβ2γ2L and α1β2A252Sγ2L receptors by the two‐electrode voltage‐clamp technique.Results:  In contrast to respective 3840‐ and 56‐fold increases in Zn2+ potencies to inhibit GABA‐ and pentobarbital‐activated currents in the α1β2 receptor, the corresponding potencies of PS remained unchanged in comparison with the α1β2γ2L receptor. A homologous mutation of the residue at 2′ position closest to the cytoplasmic end of the M2 helix to serine on both α1 and β2 subunit, α1V256S and β2A252S, abolished the inhibition of GABAA receptor by PS. In comparison with the wild type α1β2γ2L receptor, mutants α1V256Sβ2γ2L and α1β2A252Sγ2L receptors did not affect the Zn2+ inhibition. Furthermore, a significant increase in GABA potency was observed in the mutant α1V256Sβ2γ2L receptor (P < 0.05), but not the mutant α1β2A252Sγ2L receptor compared with the wild type receptor.Conclusions:  Pregnenolone sulphate was a γ2‐subunit independent inhibitor in the GABAA receptor, whereas the Zn2+ antagonism was profoundly influenced by the γ2‐subunit. It is likely that the 2′ residue closest to the N‐terminus of the protein at M2 helix on both α1 and β2 subunit are critical to the inhibitory actions of PS and the function of Cl− channels. These results are consistent with the hypothesis that PS behaves as a Cl− channel blocker that does not share with Zn2+, the coincident channel property in the GABAA receptors.
The
Pseudomonas aeruginosa
Universal Stress Protein PA4352 Is Essential for Surviving Anaerobic Energy Stress
Authors: Boes Nelli , Schreiber Kerstin , Härtig Elisabeth , Jaensch Lothar , Schobert Max 
Published: September 2006

ABSTRACT

During infection of the cystic fibrosis (CF) lung,
Pseudomonas aeruginosa
microcolonies are embedded in the anaerobic CF mucus. This anaerobic environment seems to contribute to the formation of more robust
P. aeruginosa
biofilms and to an increased antibiotic tolerance and therefore promotes persistent infection. This study characterizes the
P. aeruginosa
protein PA4352, which is important for survival under anaerobic energy stress conditions. PA4352 belongs to the universal stress protein (Usp) superfamily and harbors two Usp domains in tandem. In
Escherichia coli
, Usp-type stress proteins are involved in survival during aerobic growth arrest and under various other stresses. A
P. aeruginosa
PA4352 knockout mutant was tested for survival under several stress conditions. We found a decrease in viability of this mutant compared to the
P. aeruginosa
wild type during anaerobic energy starvation caused by the missing electron acceptors oxygen and nitrate. Consistent with this phenotype under anaerobic conditions, the PA4352 knockout mutant was also highly sensitive to carbonyl cyanide
m
-chlorophenylhydrazone, the chemical uncoupler of the electron transport chain. Primer extension experiments identified two promoters upstream of the PA4352 gene. One promoter is activated in response to oxygen limitation by the oxygen-sensing regulatory protein Anr. The center of a putative Anr binding site was identified 41.5 bp upstream of the transcriptional start site. The second promoter is active only in the stationary phase, however, independently of RpoS, RelA, or quorum sensing. This is the second
P. aeruginosa
Usp-type stress protein that we have identified as important for survival under anaerobic conditions, which resembles the environment during persistent infection.
Granular Layer in the Periplasmic Space of Gram-Positive Bacteria and Fine Structures ofEnterococcus gallinarumandStreptococcus gordoniiSepta Revealed by Cryo-Electron Microscopy of Vitreous Sections
Authors: Zuber Benoît , Haenni Marisa , Ribeiro Tânia , Minnig Kathrin , Lopes Fátima , Moreillon Philippe , Dubochet Jacques 
Published: September 2006

ABSTRACTHigh-resolution structural information on optimally preserved bacterial cells can be obtained with cryo-electron microscopy of vitreous sections. With the help of this technique, the existence of a periplasmic space between the plasma membrane and the thick peptidoglycan layer of the gram-positive bacteriaBacillus subtilisandStaphylococcus aureuswas recently shown. This raises questions about the mode of polymerization of peptidoglycan. In the present study, we report the structure of the cell envelope of three gram-positive bacteria (B. subtilis,Streptococcus gordonii, andEnterococcus gallinarum). In the three cases, a previously undescribed granular layer adjacent to the plasma membrane is found in the periplasmic space. In order to better understand how nascent peptidoglycan is incorporated into the mature peptidoglycan, we investigated cellular regions known to represent the sites of cell wall production. Each of these sites possesses a specific structure. We propose a hypothetic model of peptidoglycan polymerization that accommodates these differences: peptidoglycan precursors could be exported from the cytoplasm to the periplasmic space, where they could diffuse until they would interact with the interface between the granular layer and the thick peptidoglycan layer. They could then polymerize with mature peptidoglycan. We report cytoplasmic structures at theE. gallinarumseptum that could be interpreted as cytoskeletal elements driving cell division (FtsZ ring). Although immunoelectron microscopy and fluorescence microscopy studies have demonstrated the septal and cytoplasmic localization of FtsZ, direct visualization of in situ FtsZ filaments has not been obtained in any electron microscopy study of fixed and dehydrated bacteria.
AphB Influences Acid Tolerance of
Vibrio vulnificus
by Activating Expression of the Positive Regulator CadC
Authors: Rhee Jee Eun , Jeong Hee Gon , Lee Jeong Hyun , Choi Sang Ho 
Published: September 2006

ABSTRACT

A mutant of
Vibrio vulnificus
that was more sensitive to low pH was screened from a library of mutants constructed by random transposon mutagenesis. By use of a transposon-tagging method, an open reading frame encoding a LysR homologue, AphB, was identified and cloned from
V. vulnificus
. The deduced amino acid sequence of AphB from
V. vulnificus
was 80% identical to that reported from
V. cholerae
. A mutational analysis demonstrated that the gene product of
aphB
contributes to acid tolerance of
V. vulnificus
. The lysine decarboxylase activity and cellular level of the
cadA
transcript were decreased in the
aphB
mutant, indicating that AphB exerts its effect on the acid tolerance of
V. vulnificus
by enhancing the expression of
cadBA
. Western blot analyses demonstrated that the cellular level of CadC, a transcription activator of the
cadBA
operon, was significantly reduced by
aphB
mutation, and a primer extension analysis revealed that the
cadC
promoter (P

cadC

) activity was under the positive control of AphB. A direct interaction between AphB and the P

cadC

DNA was demonstrated by gel mobility shift assays. The AphB binding site mapped by deletion analyses of the P

cadC

regulatory region and confirmed by a DNase I protection assay was centered at the 61.5 bp upstream of the transcription start site. Accordingly, these results demonstrate that AphB and CadC function sequentially in a regulatory cascade to activate
cadBA
expression and that AphB activates the expression of
cadC
by directly binding to an upstream region of P

cadC

.
Inactivation of Rv2525c, a Substrate of the Twin Arginine Translocation (Tat) System of
Mycobacterium tuberculosis
, Increases β-Lactam Susceptibility and Virulence
Authors: Saint-Joanis Brigitte , Demangel Caroline , Jackson Mary , Brodin Priscille , Marsollier Laurent , Boshoff Helena , Cole Stewart T. 
Published: September 2006

ABSTRACT

The twin arginine translocation (Tat) system is used by many bacteria to export fully folded proteins containing cofactors. Here, we show genetically that this system is essential for
Mycobacterium tuberculosis
, as the
tatAC
operon and
tatB
genes could be inactivated only in partially diploid strains. Using comparative genomics, the rv2525c gene of
M. tuberculosis
was identified as encoding a histidine-rich protein, with a twin arginine signal peptide, and orthologous genes were shown to be present in several but not all actinobacterial species. Conservation of this gene by
Mycobacterium leprae
, which has undergone reductive evolution, suggested an important role for rv2525c. An rv2525c knockout mutant was constructed, and biochemical analysis indicated that the mature Rv2525c protein is secreted. Upon exposure to antituberculous drugs, rv2525c expression is significantly up-regulated together with those of other genes involved in cell wall biogenesis. Phenotypic comparison of the mutant with the parental strain revealed an increase in susceptibility to some β-lactam antibiotics and, despite slower growth in vitro, enhanced virulence in both cellular and murine models of tuberculosis. The Tat system thus contributes in multiple ways to survival of the tubercle bacillus.
Expression and Assembly of a Functional Type IV Secretion System Elicit Extracytoplasmic and Cytoplasmic Stress Responses inEscherichia coli
Authors: Zahrl Doris , Wagner Maria , Bischof Karin , Koraimann Günther 
Published: September 2006

ABSTRACTConditions perturbing protein homeostasis are known to induce cellular stress responses in prokaryotes and eukaryotes. Here we show for the first time that expression and assembly of a functional type IV secretion (T4S) machinery elicit extracytoplasmic and cytoplasmic stress responses inEscherichia coli. After induction of T4S genes by a nutritional upshift and assembly of functional DNA transporters encoded by plasmid R1-16, host cells activated the CpxAR envelope stress signaling system, as revealed by induction or repression of downstream targets of the CpxR response regulator. Furthermore, we observed elevated transcript levels of cytoplasmic stress genes, such asgroESL, with a concomitant increase of σ32protein levels in cells expressing T4S genes. AtraAnull mutant of plasmid R1-16, which lacks the functional gene encoding the major pilus protein pilin, showed distinctly reduced stress responses. These results corroborated our conclusion that the activation of bacterial stress networks was dependent on the presence of functional T4S machinery. Additionally, we detected increased transcription from therpoHp1promoter in the presence of an active T4S system. Stimulation ofrpoHp1was dependent on the presence of CpxR, suggesting a hitherto undocumented link between CpxAR and σ32-regulated stress networks.
Properties of Succinyl-Coenzyme A:d-Citramalate Coenzyme A Transferase and Its Role in the Autotrophic 3-Hydroxypropionate Cycle ofChloroflexus aurantiacus
Authors: Friedmann Silke , Alber Birgit E. , Fuchs Georg 
Published: September 2006

ABSTRACTThe phototrophic bacteriumChloroflexus aurantiacususes the 3-hydroxypropionate cycle for autotrophic CO2fixation. This cycle starts with acetyl-coenzyme A (CoA) and produces glyoxylate. Glyoxylate is an unconventional cell carbon precursor that needs special enzymes for assimilation. Glyoxylate is combined with propionyl-CoA to β-methylmalyl-CoA, which is converted to citramalate. Cell extracts catalyzed the succinyl-CoA-dependent conversion of citramalate to acetyl-CoA and pyruvate, the central cell carbon precursor. This reaction is due to the combined action of enzymes that were upregulated during autotrophic growth, a coenzyme A transferase with the use of succinyl-CoA as the CoA donor and a lyase cleaving citramalyl-CoA to acetyl-CoA and pyruvate. Genomic analysis identified a gene coding for a putative coenzyme A transferase. The gene was heterologously expressed inEscherichia coliand shown to code for succinyl-CoA:d-citramalate coenzyme A transferase. This enzyme, which catalyzes the reactiond-citramalate + succinyl-CoA →d-citramalyl-CoA + succinate, was purified and studied. It belongs to class III of the coenzyme A transferase enzyme family, with an aspartate residue in the active site. The homodimeric enzyme composed of 44-kDa subunits was specific for succinyl-CoA as a CoA donor but also acceptedd-malate and itaconate instead ofd-citramalate. The CoA transferase gene is part of a cluster of genes which are cotranscribed, including the gene ford-citramalyl-CoA lyase. It is proposed that the CoA transferase and the lyase catalyze the last two steps in the glyoxylate assimilation route.
Control of Enterotoxin Gene Expression in
Bacillus cereus
F4430/73 Involves the Redox-Sensitive ResDE Signal Transduction System
Authors: Duport Catherine , Zigha Assia , Rosenfeld Eric , Schmitt Philippe 
Published: September 2006

ABSTRACT

In contrast to
Bacillus subtilis
, the role of the two-component regulatory system ResDE has not yet been investigated in the facultative anaerobe
Bacillus cereus
. We examined the role of ResDE in the food-borne pathogen
B. cereus
F4430/73 by constructing
resDE
and
resE
mutants. Growth performances, glucose metabolism, and expression of hemolysin BL (Hbl) and nonhemolytic enterotoxin (Nhe) were analyzed in the three strains under distinct oxygenation and extracellular oxidoreduction potential (ORP) conditions. We show that growth and glucose metabolism were only moderately perturbed in both
resDE
and
resE
mutants under aerobiosis, microaerobiosis, and anaerobiosis generated under N
2
atmosphere (initial ORP = +45 mV). The major effects of
resDE
and
resE
mutations were observed under low-ORP anaerobic conditions generated under hydrogen atmosphere (iORP = −148 mV). These conditions normally favor enterotoxin production in the wild type. The
resE
mutation was more deleterious to the cells than the
resDE
mutation, causing growth limitation and strong deregulation of key catabolic genes. More importantly, the
resE
mutation abolished the production of enterotoxins under all of the conditions examined. The
resDE
mutation only decreased enterotoxin expression under anaerobiosis, with a more pronounced effect under low-ORP conditions. Thus, the ResDE system was found to exert major control on both fermentative growth and enterotoxin expression, and it is concluded that the ResDE system of
B. cereus
should be considered an anaerobic redox regulator. The data presented also provide evidence that the ResDE-dependent regulation of enterotoxins might function at least partially independently of the pleiotropic virulence gene regulator PlcR.