bluuebunny/crossref_metadata_2025 huggingface dataset:
Coculture Fermentations ofBifidobacteriumSpecies andBacteroides thetaiotaomicronReveal a Mechanistic Insight into the Prebiotic Effect of Inulin-Type Fructans
Authors: Falony Gwen , Calmeyn Thomas , Leroy Frédéric , De Vuyst Luc
Published: February 2009

Four bifidobacteria, each representing a cluster of strains with specific inulin-type-fructan degradation capacities, were grown in coculture fermentations withBacteroides thetaiotaomicronLMG 11262, a strain able to metabolize both oligofructose and inulin. In a medium for colon bacteria with inulin as the sole added energy source, the ability of the bifidobacteria to compete for this substrate reflected phenotypical variation.Bifidobacterium breveYakult, a strain that was not able to degrade oligofructose or inulin, was outcompeted byB. thetaiotaomicronLMG 11262.Bifidobacterium adolescentisLMG 10734, a strain that could degrade oligofructose (displaying a preferential breakdown mechanism) but that did not grow on inulin, managed to become competitive when oligofructose and short fractions of inulin started to accumulate in the fermentation medium.Bifidobacterium angulatumLMG 11039T, a strain that was previously shown to degrade all oligofructose fractions simultaneously and to be able to partially break down inulin, was competitive from the beginning of the fermentation, consuming short fractions of inulin from the moment they appeared.Bifidobacterium longumLMG 11047, representing a cluster of bifidobacteria that shared both high fructose consumption and oligofructose degradation rates and were able to perform partial breakdown of inulin, was the dominating strain in a coculture withB. thetaiotaomicronLMG 11262. These observations indicate that distinct subgroups within the large-intestinalBifidobacteriumpopulation will be stimulated by different groups of prebiotic inulin-type fructans, a variation that could be reflected in differences concerning their health-promoting effects.
Effect of Substrate Concentration on Carbon Isotope Fractionation during Acetoclastic Methanogenesis by
Methanosarcina barkeri
and
M. acetivorans
and in Rice Field Soil
Authors: Goevert Dennis , Conrad Ralf
Published: February 2009

Methanosarcina
is the only acetate-consuming genus of methanogenic archaea other than
Methanosaeta
and thus is important in methanogenic environments for the formation of the greenhouse gases methane and carbon dioxide. However, little is known about isotopic discrimination during acetoclastic CH
4
production. Therefore, we studied two species of the
Methanosarcinaceae
family,
Methanosarcina barkeri
and
Methanosarcina acetivorans
, and a methanogenic rice field soil amended with acetate. The values of the isotope enrichment factor (ε) associated with consumption of total acetate (ε
ac
), consumption of acetate-methyl (ε
ac-methyl
) and production of CH
4
(ε
CH4
) were an ε
ac
of −30.5‰, an ε
ac-methyl
of −25.6‰, and an ε
CH4
of −27.4‰ for
M. barkeri
and an ε
ac
of −35.3‰, an ε
ac-methyl
of −24.8‰, and an ε
CH4
of −23.8‰ for
M. acetivorans
. Terminal restriction fragment length polymorphism of archaeal 16S rRNA genes indicated that acetoclastic methanogenic populations in rice field soil were dominated by
Methanosarcina
spp. Isotope fractionation determined during acetoclastic methanogenesis in rice field soil resulted in an ε
ac
of −18.7‰, an ε
ac-methyl
of −16.9‰, and an ε
CH4
of −20.8‰. However, in rice field soil as well as in the pure cultures, values of ε
ac
and ε
ac-methyl
decreased as acetate concentrations decreased, eventually approaching zero. Thus, isotope fractionation of acetate carbon was apparently affected by substrate concentration. The ε values determined in pure cultures were consistent with those in rice field soil if the concentration of acetate was taken into account.
CodY in
Staphylococcus aureus
: a Regulatory Link between Metabolism and Virulence Gene Expression
Authors: Pohl Konstanze , Francois Patrice , Stenz Ludwig , Schlink Frank , Geiger Tobias , Herbert Silvia , Goerke Christiane , Schrenzel Jacques , Wolz Christiane
Published: February 2009

The repressor CodY is reported to inhibit metabolic genes mainly involved in nitrogen metabolism. We analyzed
codY
mutants from three unrelated
Staphylococcus aureus
strains (Newman, UAMS-1, and RN1HG). The mutants grew more slowly than their parent strains in a chemically defined medium. However, only
codY
mutants were able to grow in medium lacking threonine. An excess of isoleucine resulted in growth inhibition in the wild type but not in the
codY
mutants, indicating that isoleucine plays a role in CodY-dependent repression. Prototypic CodY-repressed genes including the virulence regulator
agr
are repressed after up-shift with isoleucine. The CodY-dependent repression of
agr
is consistent with the concomitant influence of CodY on typical
agr
-regulated genes such as
cap
,
spa
,
fnbA
, and
coa
. However, some of these virulence genes (e.g.,
cap
,
fnbA
, and
spa
) were also regulated by CodY in an
agr-
negative background. Microarray analysis revealed that the large majority of CodY-repressed genes were involved in amino acid metabolism; CodY-activated genes were mainly involved in nucleotide metabolism or virulence. In summary, CodY in
S. aureus
not only acts as a repressor for genes involved in nitrogen metabolism but also contributes to virulence gene regulation by supporting as well as substituting for
agr
function.
The LiaFSR System Regulates the Cell Envelope Stress Response inStreptococcus mutans
Authors: Suntharalingam Prashanth , Senadheera M. D. , Mair Richard W. , Lévesque Céline M. , Cvitkovitch Dennis G.
Published: February 2009

Maintaining cell envelope integrity is critical for bacterial survival, including bacteria living in a complex and dynamic environment such as the human oral cavity.Streptococcus mutans, a major etiological agent of dental caries, uses two-component signal transduction systems (TCSTSs) to monitor and respond to various environmental stimuli. Previous studies have shown that the LiaSR TCSTS inS. mutansregulates virulence traits such as acid tolerance and biofilm formation. Although not examined in streptococci, homologs of LiaSR are widely disseminated inFirmicutesand function as part of the cell envelope stress response network. We describe hereliaSRand its upstreamliaFgene in the cell envelope stress tolerance ofS. mutansstrain UA159. Transcriptional analysis establishedliaSRas part of the pentacistronicliaFSR-ppiB-pnpBoperon. A survey of cell envelope antimicrobials revealed that mutants deficient in one or all of theliaFSRgenes were susceptible to Lipid II cycle interfering antibiotics and to chemicals that perturbed the cell membrane integrity. These compounds inducedliaRtranscription in a concentration-dependent manner. Notably, under bacitracin stress conditions, the LiaFSR signaling system was shown to induce transcription of several genes involved in membrane protein synthesis, peptidoglycan biosynthesis, envelope chaperone/proteases, and transcriptional regulators. In the absence of an inducer such as bacitracin, LiaF repressed LiaR-regulated expression, whereas supplementing cultures with bacitracin resulted in derepression ofliaSR. While LiaF appears to be an integral component of the LiaSR signaling cascade, taken collectively, we report a novel role for LiaFSR in sensing cell envelope stress and preserving envelope integrity inS. mutans.
Mqo, a Tricarboxylic Acid Cycle Enzyme, Is Required for Virulence of
Pseudomonas syringae
pv. tomato Strain DC3000 on
Arabidopsis thaliana
Authors: Mellgren Eve M. , Kloek Andrew P. , Kunkel Barbara N.
Published: February 2009

Plant pathogenic bacteria, such as
Pseudomonas syringae
pv. tomato strain DC3000, the causative agent of tomato bacterial speck disease, grow to high levels in the apoplastic space between plant cells. Colonization of plant tissue requires expression of virulence factors that modify the apoplast to make it more suitable for pathogen growth or facilitate adaptation of the bacteria to the apoplastic environment. To identify new virulence factors involved in these processes, DC3000 Tn
5
transposon insertion mutants with reduced virulence on
Arabidopsis thaliana
were identified. In one of these mutants, the Tn
5
insertion disrupted the malate:quinone oxidoreductase gene (
mqo
), which encodes an enzyme of the tricarboxylic acid cycle.
mqo
mutants do not grow to wild-type levels in plant tissue at early time points during infection. Further, plants infected with
mqo
mutants develop significantly reduced disease symptoms, even when the growth of the
mqo
mutant reaches wild-type levels at late stages of infection. Mutants lacking
mqo
function grow more slowly in culture than wild-type bacteria when dicarboxylates are the only available carbon source. To explore whether dicarboxylates are important for growth of DC3000 in the apoplast, we disrupted the
dctA1
dicarboxylate transporter gene. DC3000 mutants lacking
dctA1
do not grow to wild-type levels in planta, indicating that transport and utilization of dicarboxylates are important for virulence of DC3000. Thus,
mqo
may be required by DC3000 to meet nutritional requirements in the apoplast and may provide insight into the mechanisms underlying the important, but poorly understood process of adaptation to the host environment.
Chemotaxis to Pyrimidines and Identification of a Cytosine Chemoreceptor in
Pseudomonas putida
Authors: Liu Xianxian , Wood Piper L. , Parales Juanito V. , Parales Rebecca E.
Published: February 2009

We developed a high-throughput quantitative capillary assay and demonstrated that
Pseudomonas putida
strains F1 and PRS2000 were attracted to cytosine, but not thymine or uracil. In contrast,
Pseudomonas aeruginosa
PAO1 was not chemotactic to any pyrimidines. Chemotaxis assays with a mutant strain of F1 in which the putative methyl-accepting chemotaxis protein-encoding gene Pput_0623 was deleted revealed that this gene (designated
mcpC
) encodes a chemoreceptor for positive chemotaxis to cytosine.
P. putida
F1 also responded weakly to cytidine, uridine, and thymidine, but these responses were not mediated by
mcpC
. Complementation of the F1 Δ
mcpC
mutant XLF004 with the wild-type gene restored chemotaxis to cytosine. In addition, introduction of this gene into
P. aeruginosa
PAO1 conferred the ability to respond to cytosine. To our knowledge, this is the first report of a chemoreceptor for cytosine.
A Vitamin B12-Based System for Conditional Expression RevealsdksATo Be an Essential Gene inMyxococcus xanthus
Authors: García-Moreno Diana , Polanco María Carmen , Navarro-Avilés Gloria , Murillo Francisco J. , Padmanabhan S. , Elías-Arnanz Montserrat
Published: February 2009

Myxococcus xanthusis a prokaryotic model system for the study of multicellular development and the response to blue light. The previous analyses of these processes and the characterization of new genes would benefit from a robust system for controlled gene expression, which has been elusive so far for this bacterium. Here, we describe a system for conditional expression of genes inM. xanthusbased on our recent finding that vitamin B12and CarH, a MerR-type transcriptional repressor, together downregulate a photoinducible promoter. Using this system, we confirmed thatM. xanthus rpoN, encoding σ54, is an essential gene, as reported earlier. We then tested it withftsZanddksA. In most bacteria,ftsZis vital due to its role in cell division, whereas null mutants ofdksA, whose product regulates the stringent response via transcriptional control of rRNA and amino acid biosynthesis promoters, are viable but cause pleiotropic effects. As withrpoN, it was impossible to delete endogenousftsZordksAinM. xanthusexcept in a merodiploid background carrying another functional copy, which indicates that these are essential genes. B12-based conditional expression offtsZwas insufficient to provide the high intracellular FtsZ levels required. WithdksA, as withrpoN, cells were viable under permissive but not restrictive conditions, and depletion of DksA or σ54produced filamentous, aberrantly dividing cells.dksAthus joinsrpoNin a growing list of genes dispensable in many bacteria but essential inM. xanthus.
Phylogeography of
Francisella tularensis
: Global Expansion of a Highly Fit Clone
Authors: Vogler Amy J. , Birdsell Dawn , Price Lance B. , Bowers Jolene R. , Beckstrom-Sternberg Stephen M. , Auerbach Raymond K. , Beckstrom-Sternberg James S. , Johansson Anders , Clare Ashley , Buchhagen Jordan L. , Petersen Jeannine M. , Pearson Talima , Vaissaire Josée , Dempsey Michael P. , Foxall Paul , Engelthaler David M. , Wagner David M. , Keim Paul
Published: February 2009

Francisella tularensis
contains several highly pathogenic subspecies, including
Francisella tularensis
subsp.
holarctica
, whose distribution is circumpolar in the northern hemisphere. The phylogeography of these subspecies and their subclades was examined using whole-genome single nucleotide polymorphism (SNP) analysis, high-density microarray SNP genotyping, and real-time-PCR-based canonical SNP (canSNP) assays. Almost 30,000 SNPs were identified among 13 whole genomes for phylogenetic analysis. We selected 1,655 SNPs to genotype 95 isolates on a high-density microarray platform. Finally, 23 clade- and subclade-specific canSNPs were identified and used to genotype 496 isolates to establish global geographic genetic patterns. We confirm previous findings concerning the four subspecies and two
Francisella tularensis
subsp.
tularensis
subpopulations and identify additional structure within these groups. We identify 11 subclades within
F. tularensis
subsp.
holarctica
, including a new, genetically distinct subclade that appears intermediate between Japanese
F. tularensis
subsp.
holarctica
isolates and the common
F. tularensis
subsp.
holarctica
isolates associated with the radiation event (the B radiation) wherein this subspecies spread throughout the northern hemisphere. Phylogenetic analyses suggest a North American origin for this B-radiation clade and multiple dispersal events between North America and Eurasia. These findings indicate a complex transmission history for
F. tularensis
subsp.
holarctica
.
Manual Annotation, Transcriptional Analysis, and Protein Expression Studies Reveal Novel Genes in the
agl
Cluster Responsible for N Glycosylation in the Halophilic Archaeon
Haloferax volcanii
Authors: Yurist-Doutsch Sophie , Eichler Jerry
Published: February 2009

While
Eukarya
,
Bacteria
, and
Archaea
are all capable of protein N glycosylation, the archaeal version of this posttranslational modification is the least understood. To redress this imbalance, recent studies of the halophilic archaeon
Haloferax volcanii
have identified a gene cluster encoding the Agl proteins involved in the assembly and attachment of a pentasaccharide to select Asn residues of the surface layer glycoprotein in this species. However, because the automated tools used for rapid annotation of genome sequences, including that of
H. volcanii
, are not always accurate, a reannotation of the
agl
cluster was undertaken in order to discover genes not previously recognized. In the present report, reanalysis of the gene cluster that includes
aglB
,
aglE
,
aglF
,
aglG
,
aglI
, and
aglJ
, which are known components of the
H. volcanii
protein N-glycosylation machinery, was undertaken. Using computer-based tools or visual inspection, together with transcriptional analysis and protein expression approaches, genes encoding AglP, AglQ, and AglR are now described.
UEFA injury study—an injury audit of European Championships 2006 to 2008
Authors: Hägglund M , Waldén M , Ekstrand J
Published: February 2009

Objective:

To study the incidence and nature of injuries at European Championships, to compare training and match injury characteristics and to study differences in injury incidence between tournaments.

Design:

Team physicians prospectively recorded individual player exposure and time loss injuries during 12 European Championships (men’s EURO n = 1, men’s Under-21 n = 2, men’s Under-19 n = 3, men’s Under-17 n = 3, women’s Under-19 n = 3) from 2006 to 2008.

Setting:

International football tournaments

Participants:

1594 men and 433 women

Main outcome measurement:

Injury incidence

Results:

224 injuries (45 training, 179 match play) were registered among 208 (10%) players. No differences in training injury incidence were seen between tournaments (range 1.3–3.9 injuries/1000 hours). The men’s EURO had the highest match injury incidence (41.6 injuries/1000 hours) followed by the men’s Under-21 tournaments (33.9). The lowest match injury incidence was seen in the women’s Under-19 tournaments (20.5). Training injuries constituted 20% of all injuries and caused 26% of all match unavailability. A greater proportion of match injuries were due to trauma (83 vs 47%, p<0.001) and occurred from player contact (75 vs 48%, p = 0.018) compared to training injuries. A higher frequency of re-injury was found among training injuries than match injuries (20 vs 6%, p = 0.009).

Conclusions:

Match injury incidence increased with age, indicating greater risk with higher intensity of play. Training injury incidence was relatively low, but training injuries were responsible for a quarter of all match unavailability and may thus have a profound impact on team performance and should be the object of preventive measures.
Adipokines and the clinical laboratory: what to measure, when and how?
Authors: Hill M J , Kumar S , McTernan P G
Published: February 2009

This review summarises current experimental adipokine investigations and will focus on some of the procedures and techniques that are currently important in the clinical research laboratory. The complexity of measuring adipokines is discussed and the relative success of the various applications in the transition from the laboratory to clinical diagnosis assessed. In addition, as new adipokines continue to emerge, this review will consider the direction research is taking at the cutting edge of novel adipokine discovery. Finally, how a more comprehensive understanding of the pathobiology related to adipokines may enhance innovative therapeutic strategies designed to attenuate the predicted explosion in obesity related diseases will be discussed.
Paradoxical decreases in high-density lipoprotein cholesterol with fenofibrate: a quite common phenomenon
Authors: Magee G , Sharpe P C
Published: February 2009

Background:

Reduced high-density lipoprotein cholesterol (HDL-C) concentration is considered to be an independent risk factor for cardiovascular morbidity and mortality. Fibrates are useful in managing dyslipidaemia; reports highlight an expected increase in HDL-C of 10–15% in conjunction with falls in plasma triglycerides of ∼30%. Despite this, there are several reported cases of paradoxical decreases in HDL-C caused by fibrate treatment.

Aim:

To report the second largest observational study to date.

Methods:

Fenofibrate use at a regional lipid clinic was associated with reductions in HDL-C in a considerable proportion of patients, necessitating cessation of the medication. In view of this, characteristics of the first 94 patients to be given fenofibrate were retrospectively analysed, and comparisons were made between those whose profiles responded as expected and those experiencing paradoxical decreases in HDL-C.

Results:

94 patients (57 male; mean (SD) age 52.5 (12.5) years; mean (SD) body mass index 28.9 (4.5) kg/m2) were assessed. After 8–12 weeks on daily fenofibrate (200 mg micronised or equivalent), 43 of the patients (46%) showed a paradoxical decrease in HDL-C (in nine the decrease was >50% from baseline). When responses to fenofibrate were compared against baseline variables, there were no significant differences between groups other than a higher baseline HDL-C (p = 0.045) in patients responding appropriately.

Conclusions:

Fenofibrate was associated with a reduction in HDL-C in almost half the patients studied. This is substantially more than in most studies reported to date. Other HDL-C-raising strategies need to be considered in these patients, and the mechanisms need to be explored.
Subjects’ views of obligations to ensure post-trial access to drugs, care and information: qualitative results from the Experiences of Participants in Clinical Trials (EPIC) study
Authors: Sofaer N , Thiessen C , Goold S D , Ballou J , Getz K A , Koski G , Krueger R A , Weissman J S
Published: February 2009

Objectives:

To report the attitudes and opinions of subjects in US clinical trials about whether or not, and why, they should receive post-trial access (PTA) to the trial drug, care and information.

Design:

Focus groups, short self-administered questionnaires.

Setting:

Boston, Dallas, Detroit, Oklahoma City.

Participants:

Current and recent subjects in clinical trials, primarily for chronic diseases.

Results:

93 individuals participated in 10 focus groups. Many thought researchers, sponsors, health insurers and others share obligations to facilitate PTA to the trial drug, if it benefited the subject, or to a therapeutic equivalent. Some thought PTA obligations include providing transition care (referrals to non-trial physicians or other trials, limited follow-up, short-term drug supply) or care for long-term adverse events. Others held, in contrast, that there are no PTA obligations regarding drugs or care. However, there was agreement that former subjects should receive information (drug name, dosage received, market approval date, long-term adverse effects, trial results). Participants frequently appealed to health need, cost, relationships, reciprocity, free choice and sponsor self-interest to support their views. Many of their reasons overlapped with those commonly discussed by bioethicists.

Conclusion:

Many participants in US trials for chronic conditions thought there are obligations to facilitate PTA to the trial drug at a “fair” price; these views were less demanding than those of non-US subjects in other studies. However, our participants’ views about informational obligations were broader than those of other subjects and many bioethicists. Our results suggest that the PTA debate should expand beyond the trial drug and aggregate results.
Responsibility as a meta-virtue: truth-telling, deliberation and wisdom in medical professionalism
Authors: Barilan Y M
Published: February 2009

The article examines the new discourse on medical professionalism and responsibility through the prism of conflicts among moral values, especially with regard to truth-telling.

The discussion is anchored in the renaissance of English-language writing on medical ethics in the 18thcentury, which paralleled the rise of humanitarianism and the advent of the word “responsibility”.

Following an analysis of the meanings of the value of responsibility in general and in medical practice in particular, it is argued that, similarly to the Aristotelian notion of equity, responsibility of care is a second-order value, which corrects virtues, laws and norms in exceptional circumstances.

Virtues and practices of the second order, such as responsibility and deliberation, bear especially on professional doctoring, which includes a commitment to give priority to the good of the patient over one’s own good.

It is argued that, in situations of conflict, and particularly conflicts between personal moral identity and the good of patients, the fundamental professional commitment is to critical and rational deliberation and to the cultivation of psycho-moral flexibility. This leads indirectly to moral growth and strengthening of professional character.
The high incidence and bioethics of findings on magnetic resonance brain imaging of normal volunteers for neuroscience research
Authors: Hoggard N , Darwent G , Capener D , Wilkinson I D , Griffiths P D
Published: February 2009

Background:

We were finding volunteers for functional magnetic resonance imaging studies with abnormalities requiring referral surprisingly frequently. The bioethics surrounding the incidental findings are not straightforward and every imaging institution will encounter this situation in their normal volunteers. Yet the implications for the individuals involved may be profound. Should all participants have review of their imaging by an expert and who should be informed?

Methods:

The normal volunteers that were imaged with magnetic resonance (MR) which were reviewed by a consultant neuroradiologist. All participants completed a volunteer consent form in addition to a standard departmental MR safety screening form. The volunteer screening form requires the general practitioner details to be completed and asks the participant to consider closely the possibility and implications of finding an unexpected but potentially serious abnormality before signing.

Results:

525 different individuals were scanned as normal volunteers, the mean age was 35-years and 330 were males. Of these 525, 46 had definite significant abnormalities (8.8%), mean age 50-years.

Conclusion:

We have found a high rate of incidental abnormalities amongst individuals participating in imaging studies at our institution. It is our current practice to inform the research study participant of the findings, counsel them and inform their primary care physician. We think that it is advisable for researchers utilising MR imaging of the brain to have access to trained neuroradiologists, a protocol in place to deal with this problem and take consent in a way that allows the participant to realise the possibility of an abnormal finding.
What is happening during case deliberations in clinical ethics committees? A pilot study: Table 1
Authors: Pedersen R , Akre V , Førde R
Published: February 2009

Background:

Clinical ethics consultation services have been established in many countries during recent decades. An important task is to discuss concrete clinical cases. However, empirical research observing what is happening during such deliberations is scarce.

Objectives:

To explore clinical ethics committees’ deliberations and to identify areas for improvement.

Design:

A pilot study including observations of committees deliberating a paper case, semistructured group interviews, and qualitative analysis of the data.

Participants:

Nine hospital ethics committees in Norway.

Results and interpretations:

Key elements of the deliberations included identifying the ethical problems; exploring moral values and principles; clarifying key concepts and relevant legal regulation; exploring medical facts, the patient’s situation, the therapists’ perspective, analogous clinical situations, professional uncertainties, the patient’s and relatives’ perspective, and clinical communication; identifying the involved parties and how to involve them; identifying possible courses of action, and possible conclusion and follow-up. The various elements were closely interwoven. The content and conclusions varied and seemed to be contingent on the committee members’ interpretations, experience and knowledge. Important aspects of a clinical ethics deliberation were sometimes neglected. When the committees used a deliberation procedure and a blackboard, the deliberations tended to become more systematic and transparent. Many of the committees were insecure about how to include the involved parties and how to document the deliberations.

Conclusion:

Clinical ethics committees may provide an important arena for multidisciplinary discussions of complex clinical ethics challenges. However, this seems to require adequate composition, adoption of transparent deliberation procedures, and targeted training.
HARD-POMERON BEHAVIOR OF THE LONGITUDINAL STRUCTURE FUNCTION FL IN THE NEXT-TO-LEADING ORDER AT LOW x
Authors: BOROUN G. R.
Published: February 2009

We present an analytic formula to extract the longitudinal structure function in the next-to-leading order of the perturbation theory at low x, from the Regge-like behavior of the gluon distribution and the structure function at this limit. In this approach, the longitudinal structure function has the hard-Pomeron behavior. The determined values are compared with the H1 data and MRST model. All results can consistently be described within the framework of perturbative QCD, which essentially show increases as x decreases.
A NUMERICAL CLUSTER MODEL WITH SHELL MODEL ASSUMPTIONS
Authors: HASSAN MOHAMED AHMED
Published: February 2009

A numerical representation for nuclei is suggested and considered as a basis of a cluster model. The binding energy of the cluster representation of a nucleus is introduced. Basic assumptions of the shell model are obtained as the physical side of the suggested cluster representation. 8 Be 4-decay to two α-particles and 9 B 5 decay to two α-particles and proton are interpreted.
TORELLI THEOREM FOR MODULI SPACES OF SL(r,ℂ)-CONNECTIONS ON A COMPACT RIEMANN SURFACE
Authors: BISWAS INDRANIL , MUÑOZ VICENTE
Published: February 2009

Let X be any compact connected Riemann surface of genus g, with g ≥ 3. For any r ≥ 2, let [Formula: see text] denote the moduli space of holomorphic SL (r,ℂ)-connections over X. It is known that the biholomorphism class of the complex variety [Formula: see text] is independent of the complex structure of X. If g = 3, then we assume that r ≥ 3. We prove that the isomorphism class of the variety [Formula: see text] determines the Riemann surface X uniquely up to an isomorphism. A similar result is proved for the moduli space of holomorphic GL (r,ℂ)-connections on X.

We also show that the Torelli theorem remains valid for the moduli spaces of connections, as well as those of stable vector bundles, on geometrically irreducible smooth projective curves defined over the field of real numbers.
L2-CONCENTRATION PHENOMENON FOR ZAKHAROV SYSTEM BELOW ENERGY NORM
Authors: FANG DAOYUAN , ZHONG SIJIA
Published: February 2009

In this paper, we prove an L2-concentration result of Zakharov system in space dimension two, with radial initial data [Formula: see text], when blow up of the solution happens by I-method. In addition to that, we find a blow up character of this system. Furthermore, we improve the global existence result of Bourgain's to the above-mentioned spaces.
ZERO ORDER PERTURBATIONS TO FULLY NONLINEAR EQUATIONS: COMPARISON, EXISTENCE AND UNIQUENESS
Authors: CHARRO FERNANDO , PERAL IRENEO
Published: February 2009

We study existence of solutions to [Formula: see text] where F is elliptic and homogeneous of degree m, and either f(λ,u) = λ uqor f(λ,u) = λ uq+ ur, for 0 < q < m < r, and λ > 0. Furthermore, in the first case, we obtain that the solution is unique as a consequence of a comparison principle up to the boundary. Several examples, including uniformly elliptic operators and the infinity-laplacian, are considered.
Comprehensive refertilization of lithospheric mantle beneath the North China Craton: further Os–Sr–Nd isotopic constraints
Authors: Zhang Hong-Fu , Goldstein Steven L. , Zhou Xin-Hua , Sun Min , Cai Yue
Published: February 2009

Mantle peridotitic xenoliths in Cenozoic basalts from Hannuoba, on the northern margin of the Archaean North China Craton, have variable Re (0.01–0.30 ppb) and Os (2.7–6.2 ppb) abundances and
187
Os/
188
Os (0.1138–0.1236) ratios. These xenoliths yield a range of Proterozoic Re depletion ages of 0.8–2.2 Ga that show a general correlation with olivine Fo. Mantle xenoliths in Cenozoic basalts from the centre and southern margin of the North China Craton also overwhelmingly show Proterozoic Re depletion ages that correlate with olivine Fo. These Re–Os age features are completely different from those of Palaeozoic kimberlite-borne peridotitic xenoliths, which have Archaean ages. This age distinction between xenoliths associated with Palaeozoic and Cenozoic volcanism indicates that the present-day lithospheric mantle was dominantly not newly accreted during the Phanerozoic but instead was transformed from the ancient lithospheric mantle by interaction with melts. The Re–Os data in combination with the geochemical and Sr–Nd isotopic features of peridotitic xenoliths from the Cenozoic basalts of the North China Craton demonstrate the presence of multiple stages of mantle metasomatic overprints in the lithospheric mantle. This study thus further indicates that lithospheric transformation through melt–rock interaction could be an important mechanism for compositional refertilization during the Phanerozoic.

Supplementary material:

Analytical methods and geochemical data are available at
http://www.geolsoc.org.uk/SUP18334
.
Fault-assisted vertical pluton growth: Coastal Cordillera, north Chilean Andes
Authors: Grocott John , Arévalo Carlos , Welkner Daniela , Cruden Alexander
Published: February 2009

Extensive tracts of magmatic arc plutonic suites in the Mesozoic Coastal Cordillera of northern Chile imply that large volumes of granitic to dioritic magmas were transferred from a lower crustal source to the upper crust. Space for single intrusions was created by interaction of vertical pluton growth and dip-slip reactivation of arc-parallel faults during episodic emplacement of subhorizontal, compositionally distinct magma pulses. Cross-sectional pluton shapes are broadly tabular in geometry and were controlled by differential subsidence of the pluton floors during fault reactivation and incremental assembly of subhorizontal sheets. Equal amounts of floor subsidence of the fault footwall and hanging wall during magma accommodation led to symmetrical intrusions, whereas differential subsidence caused plutons to grow asymmetrically. Strongly asymmetrical plutons resulted when only the hanging wall was reactivated to accommodate floor subsidence. Late, post-intrusion contractional deformation resulted in open folding of some tabular plutonic units and local inversion of bounding faults, which has modified but not obscured the original syn-emplacement geometry and fault kinematics.
Evolutionary relationships within the Avalonian Ediacara biota: new insights from laser analysis
Authors: Brasier Martin D. , Antcliffe Jonathan B.
Published: February 2009

We report new high-resolution laser scanning of the type material for the earliest, complex Ediacaran genera
Charnia
,
Bradgatia
,
Charniodiscus
and
Ivesheadia
from Charnwood, UK, and compare these with
Beothukis mistakensis
gen. et sp. nov. and the recently described taxa
Charnia wardi
,
Charnia antecedens
and
Fractofusus
spp. from broadly coeval strata in Newfoundland. We use the laser and other techniques to map the similarities and differences in morphology between these Ediacaran rangeomorphs. Key features are suggested to include the number of growth axes, the number and placement of growth tips, the presence of radiating or subparallel axes for the first- and higher-order branches, the extent of displayed or undisplayed leaf-like ’rangeomorph' architecture, and the extent of furling of the margins of these leaf-like elements. These features are then used to propose suggested homologies between these taxa, leading to a preliminary phylogenetic hypothesis for the evolution of the Avalonian Ediacara biota.
U–Pb detrital zircon ages and Sm–Nd isotopic features in low-grade metasedimentary rocks of the Famatina belt: implications for late Neoproterozoic–early Palaeozoic evolution of the proto-Andean margin of Gondwana
Authors: Collo Gilda , Astini Ricardo A. , Cawood Peter A. , Buchan Craig , Pimentel Marcio
Published: February 2009

The Famatina belt, Central Andes, is part of an ancient accretionary margin built along Western Gondwana in the early Palaeozoic. U–Pb ion microprobe analysis of detrital zircons and Sm–Nd whole-rock analysis of two early Palaeozoic low-grade metasedimentary units record the early evolution of this region. Detrital zircons in the Negro Peinado and Achavil formations have ages ranging from Palaeoproterozoic to Cambrian, consistent with derivation from Gondwanan sources. T
DM
ages suggest that the sedimentary rocks were derived from a composite source area, which separated from the mantle during the Palaeoproterozoic (
c
. 1.8–1.6 Ga). Constraints from the youngest detrital grains indicate accumulation in a Mid- to Late Cambrian foreland basin adjacent to the inboard Pampean orogenic tract. The dominance of Cambrian ages in the Negro Peinado Formation suggests derivation principally from the eastern Pampean belt whereas the dominance of late Neoproterozoic ages in the Achavil Formation suggests that input from the Pampean belt was overwhelmed by older sources. The paucity of Palaeoproterozoic ages argues against direct input from older areas such as the Río de la Plata craton. The predominance of Meso- and Neoproterozoic ages over older sources suggests that a Brasiliano-age magmatic arc developed on a Mesoproterozoic basement, probably a southern extension of the Arequipa–Antofalla massif.
Exhumation of a Cretaceous rift complex within a Late Cenozoic restraining bend, southern Mongolia: implications for the crustal evolution of the Gobi Altai region
Authors: Cunningham Dickson , Davies Sarah , McLean Duncan
Published: February 2009

The Gobi Altai region of southern Mongolia contains intramontane basins dominated by Jurassic–Cretaceous clastic and volcanic deposits. The origin of the basins is poorly documented because Late Cenozoic transpressional mountain building and associated alluvial sedimentation have overprinted and obscured the older Mesozoic history. In this study, we report the discovery of Cretaceous high-angle normal faults and a major low-angle extensional detachment fault bordering the Altan Uul range in southern Mongolia, which indicates that NW–SE crustal stretching was responsible for creating the accommodation space for thick Jurassic–Cretaceous sedimentary accumulations in southern Mongolia. The detachment fault separates chlorite-grade metasedimentary rocks in the footwall from intensely sheared and flattened unmetamorphosed conglomerates and breccias in the hanging wall. The significant metamorphic break across the detachment fault, associated extensional structures in the hanging wall, and domal form of the footwall block indicate that NW Altan Uul has some structural and topographic characteristics typically associated with metamorphic core complexes. However, NW Altan Uul lacks ductile extensional fabrics along the detachment fault and in the adjacent footwall, and limited stretching in the upper plate suggests less total extensional slip than is reported from typical metamorphic core complexes. Unconformable relations in hanging-wall strata and palynological data indicate that extensional detachment faulting at NW Altan Uul occurred in the Aptian (120–112 Ma) similar in time to metamorphic core complex development previously reported in Mongolia–China border areas and the Daqing Shan of northern China. Post-detachment fault Cretaceous sedimentation buried NW Altan Uul, which is now exposed only as a result of erosional denudation associated with uplift of the recent Nemegt–Altan Uul restraining bend. The discovery of significant Aptian crustal extension in the southern Gobi Altai suggests that Early Cretaceous diffuse rifting encompassed an even wider region than was previously recognized, including areas of the eastern Altai, central, southern and eastern Mongolia, and adjacent areas of northern and northeastern China and Transbaikalia, constituting one of Earth's largest continental interior extensional provinces. Workers investigating the neotectonic development of the Gobi Altai should consider the extent to which the pre-existing rift basin architecture may have influenced the recent range development and network of seismically active faults in the region.
Evidence for an early Archaean granite from Bastar craton, India
Authors: Rajesh H.M. , Mukhopadhyay J. , Beukes N.J. , Gutzmer J. , Belyanin G.A. , Armstrong R.A.
Published: February 2009

Granitoids in the early Archaean are believed to be potassium-poor tonalite–trondhjemite–granodiorite rocks. Only after continental crust attained sufficient thickness did true (relatively potassium-rich) granites form. No record of true granite prior to 3.4 Ga is available. We report a 3.6 Ga true granite from the Archaean Bastar craton in India. In contrast to the typical early Archaean granitoids, which are commonly deformed into gneisses, this granite is relatively undeformed. The age and composition of the granite implies that continental crust of the Bastar craton attained sufficient thickness to permit intracrustal melting at 3.6 Ga.

Supplementary material:

Representative major element, trace element and REE composition of the Dalli-Rajhara granite samples and a summary of SHRIMP U-Pb zircon data for the granite sample D-9 are available at
http://www.geolsoc.org.uk/SUP18337
.
Small intestinal MUC2 synthesis in human preterm infants
Authors: Schaart Maaike W. , de Bruijn Adrianus C. J. M. , Schierbeek Henk , Tibboel Dick , Renes Ingrid B. , van Goudoever Johannes B.
Published: February 2009

Mucin 2 (MUC2) is the structural component of the intestinal protective mucus layer, which contains high amounts of threonine in its peptide backbone. MUC2 synthesis rate might be a potential parameter for intestinal barrier function. In this study, we aimed to determine whether systemic threonine was used for small intestinal MUC2 synthesis and to calculate the MUC2 fractional synthetic rate (FSR) in human preterm infants. Seven preterm infants with an enterostomy following bowel resection for necrotizing enterocolitis received intravenous infusion of [U-13C]threonine to determine incorporation of systemic threonine into secreted MUC2 in intestinal outflow fluid. Small intestinal MUC2 was isolated using cesium chloride gradient ultracentrifugation and gravity gel filtration chromatography. MUC2-containing fractions were identified by SDS-PAGE/periodic acid-Schiff staining and Western blot analysis and were subsequently pooled. Isotopic enrichment of threonine, measured in MUC2 using gas chromatography isotopic ratio mass spectrometry, was used to calculate the FSR of MUC2. Systemically derived threonine was indeed incorporated into small intestinal MUC2. Median FSR of small intestinal MUC2 was 67.2 (44.3–103.9)% per day. Systemic threonine is rapidly incorporated into MUC2 in the small intestine of preterm infants, and thereby MUC2 has a very high synthesis rate.
ANG II infusion promotes abdominal aortic aneurysms independent of increased blood pressure in hypercholesterolemic mice
Authors: Cassis Lisa A. , Gupte Manisha , Thayer Sarah , Zhang Xuan , Charnigo Richard , Howatt Deborah A. , Rateri Debra L. , Daugherty Alan
Published: February 2009

Infusion of ANG II in hyperlipidemic mice augments atherosclerosis and causes formation of abdominal aortic aneurysms (AAAs). The purpose of this study was to define the contribution of ANG II-induced hypertension to these vascular pathologies. Male apolipoprotein E (apoE)- and LDL receptor (LDLr)-deficient mice were infused with ANG II (1,000 ng·kg−1·min−1) or norepinephrine (NE; 5.6 mg·kg−1·day−1) for 28 days. Infusion of ANG II or NE increased mean arterial pressure (MAP; ANG II, 133 ± 2.8; NE, 129 ± 13 mmHg) to a similar extent compared with baseline blood pressures (MAP, 107 ± 2 mmHg). Abdominal aortic width increased in both apoE-deficient (apoE−/−) or LDLr-deficient (LDLr−/−) mice infused with ANG II (apoE−/−: 1.4 ± 0.1; LDLr−/−: 1.6 ± 0.2 mm). In contrast, NE did not change diameters of abdominal aortas (apoE−/−: 0.91 ± 0.03; LDLr−/−: 0.87 ± 0.02 mm). Similarly, atherosclerotic lesions in aortic arches were much greater in mice infused with ANG II compared with NE. At a subpressor infusion rate of ANG II (500 ng·kg−1·min−1), AAAs developed in 50% of apoE−/− mice. Alternatively, administration of hydralazine (250 mg/l) to ANG II-infused apoE−/− mice (1,000 ng·kg−1·min−1) lowered systolic blood pressure ( day 28: ANG II, 157 ± 6; ANG II/hydralazine, 135 ± 6 mmHg) but did not prevent AAA formation or atherosclerosis. These results demonstrate that infusion of ANG II to hyperlipidemic mice induces AAAs and augments atherosclerosis independent of increased blood pressure.
Angiotensin II disproportionally attenuates dynamic vagal and sympathetic heart rate controls
Authors: Kawada Toru , Mizuno Masaki , Shimizu Shuji , Uemura Kazunori , Kamiya Atsunori , Sugimachi Masaru
Published: February 2009

To better understand the pathophysiological role of angiotensin II (ANG II) in the dynamic autonomic regulation of heart rate (HR), we examined the effects of intravenous administration of ANG II (10 μg·kg−1·h−1) on the transfer function from vagal or sympathetic nerve stimulation to HR in anesthetized rabbits with sinoaortic denervation and vagotomy. In the vagal stimulation group ( n = 7), we stimulated the right vagal nerve for 10 min using binary white noise (0–10 Hz). The transfer function from vagal stimulation to HR approximated a first-order low-pass filter with pure delay. ANG II attenuated the dynamic gain from 7.6 ± 0.9 to 5.8 ± 0.9 beats·min−1·Hz−1(means ± SD; P < 0.01) without affecting the corner frequency or pure delay. In the sympathetic stimulation group ( n = 7), we stimulated the right postganglionic cardiac sympathetic nerve for 20 min using binary white noise (0–5 Hz). The transfer function from sympathetic stimulation to HR approximated a second-order low-pass filter with pure delay. ANG II slightly attenuated the dynamic gain from 10.8 ± 2.6 to 10.2 ± 3.1 beats·min−1·Hz−1( P = 0.049) without affecting the natural frequency, damping ratio, or pure delay. The disproportional suppression of the dynamic vagal and sympathetic regulation of HR would result in a relative sympathetic predominance in the presence of ANG II. The reduced high-frequency component of HR variability in patients with cardiovascular diseases, such as myocardial infarction and heart failure, may be explained in part by the peripheral effects of ANG II on the dynamic autonomic regulation of HR.
Iloprost- and isoproterenol-induced increases in cAMP are regulated by different phosphodiesterases in erythrocytes of both rabbits and humans
Authors: Adderley Shaquria P. , Dufaux Eileen A. , Sridharan Meera , Bowles Elizabeth A. , Hanson Madelyn S. , Stephenson Alan H. , Ellsworth Mary L. , Sprague Randy S.
Published: February 2009

Activation of the G protein Gsresults in increases in cAMP, a necessary step in the pathway for ATP release from rabbit and human erythrocytes. In all cells, the level of cAMP is the product of its synthesis by adenylyl cyclase and its hydrolysis by phosphodiesterases (PDEs). Both iloprost (Ilo), a PGI2analog, and isoproterenol (Iso), a β-agonist, stimulate receptor-mediated increases in cAMP in rabbit and human erythrocytes. However, the specific PDEs associated with each of these signaling pathways in the erythrocyte have not been fully characterized. Previously, we reported that PDE3B is present in rabbit and human erythrocyte membranes and that PDE3 inhibitors potentiate Ilo-induced increases in cAMP. Here we report that inhibitors of either PDE2 or PDE4, erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) and rolipram, respectively, potentiate Iso-induced increases in cAMP in rabbit and human erythrocytes. Importantly, these inhibitors had no effect on cAMP increases associated with the incubation of erythrocytes with Ilo. In addition, we establish, for the first time, the presence of PDE2A protein in rabbit and human erythrocyte membranes. Finally, we determined that preincubation of human erythrocytes with EHNA and rolipram together potentiate Iso-induced ATP release, whereas preincubation with cilostazol enhances Ilo-induced release of ATP. These results are consistent with the hypothesis that, in rabbit and human erythrocytes, Ilo-induced increases in cAMP and ATP release are regulated by PDE3, whereas those associated with Iso are regulated by the activities of both PDE2 and PDE4. These studies demonstrate that PDE activity in these cells is localized to specific signaling pathways.