bluuebunny/crossref_metadata_2025 huggingface dataset:
A role for the Rcs phosphorelay in regulating expression of plant cell wall degrading enzymes in Pectobacterium carotovorum subsp. carotovorum
Authors: Andresen Liis , Sala Erki , Kõiv Viia , Mäe Andres
Published: January 2010

The Rcs phosphorelay is a signal transduction system that influences the virulence phenotype of several pathogenic bacteria. In the plant pathogen Pectobacterium carotovorum subsp. carotovorum (Pcc) the response regulator of the Rcs phosphorelay, RcsB, represses expression of plant cell wall degrading enzymes (PCWDE) and motility. The focus of this study was to identify genes directly regulated by the binding of RcsB that also regulate expression of PCWDE genes in Pcc. RcsB-binding sites within the regulatory regions of the flhDC operon and the rprA and rsmB genes were identified using DNase I protection assays, while in vivo studies using flhDC : : gusA, rsmB : : gusA and rprA : : gusA gene fusions revealed gene regulation. These experiments demonstrated that the operon flhDC, a flagellar master regulator, was repressed by RcsB, and transcription of rprA was activated by RcsB. Regulation of the rsmB promoter by RcsB is more complicated. Our results show that RcsB represses rsmB expression mainly through modulating flhDC transcription. Neverthless, direct binding of RcsB on the rsmB promoter region is possible in certain conditions. Using an rprA-negative mutant, it was further demonstrated that RprA RNA is not essential for regulating expression of PCWDE under the conditions tested, whereas overexpression of rprA increased protease expression in wild-type cells. Stationary-phase sigma factor, RpoS, is the only known target gene for RprA RNA in Escherichia coli; however, in Pcc the effect of RprA RNA was found to be rpoS-independent. Overall, our results show that the Rcs phosphorelay negatively affects expression of PCWDE by inhibiting expression of flhDC and rsmB.
Evaluation of the effects of sdiA, a luxR homologue, on adherence and motility of Escherichia coli O157 : H7
Authors: Sharma Vijay K. , Bearson Shawn M. D. , Bearson Bradley L.
Published: January 2010

Quorum-sensing (QS) signalling pathways are important regulatory networks for controlling the expression of genes promoting adherence of enterohaemorrhagic Escherichia coli (EHEC) O157 : H7 to epithelial cells. A recent study has shown that EHEC O157 : H7 encodes a luxR homologue, called sdiA, which upon overexpression reduces the expression of genes encoding flagellar and locus of enterocyte effacement (LEE) proteins, thus negatively impacting on the motility and intimate adherence phenotypes, respectively. Here, we show that the deletion of sdiA from EHEC O157 : H7 strain 86-24, and from a hha (a negative regulator of ler) mutant of this strain, enhanced bacterial adherence to HEp-2 epithelial cells of the sdiA mutant strains relative to the strains containing a wild-type copy of sdiA. Quantitative reverse transcription PCR showed that the expression of LEE-encoded genes ler, espA and eae in strains with the sdiA deletions was not significantly different from that of the strains wild-type for sdiA. Similarly, no additional increases in the expression of LEE genes were observed in a sdiA hha double mutant strain relative to that observed in the hha deletion mutant. While the expression of fliC, which encodes flagellin, was enhanced in the sdiA mutant strain, the expression of fliC was reduced by several fold in the hha mutant strain, irrespective of the presence or absence of sdiA, indicating that the genes sdiA and hha exert opposing effects on the expression of fliC. The strains with deletions in sdiA or hha showed enhanced expression of csgA, encoding curlin of the curli fimbriae, with the expression of csgA highest in the sdiA hha double mutant, suggesting an additive effect of these two gene deletions on the expression of csgA. No significant differences were observed in the expression of the genes lpfA and fimA of the operons encoding long polar and type 1 fimbriae in the sdiA mutant strain. These data indicate that SdiA has no significant effect on the expression of LEE genes, but that it appears to act as a strong repressor of genes encoding flagella and curli fimbriae, and the alleviation of the SdiA-mediated repression of these genes in an EHEC O157 : H7 sdiA mutant strain contributes to enhanced bacterial motility and increased adherence to HEp-2 epithelial cells.
Effects of spontaneous mutations in PipX functions and regulatory complexes on the cyanobacterium Synechococcus elongatus strain PCC 7942
Authors: Espinosa Javier , Castells Miguel Angel , Laichoubi Karim Boumediene , Forchhammer Karl , Contreras Asunción
Published: January 2010

InSynechococcus elongatussp. PCC 7942, PipX forms complexes with PII, a protein found in all three domains of life as an integrator of signals of the nitrogen and carbon balance, and with the cyanobacterial nitrogen regulator NtcA. We recently showed that previous inactivation ofpipXfacilitates subsequent inactivation of theglnBgene. Here, we show that the three spontaneouspipXpoint mutationspipX-92delT,pipX160C>TandpipX194T>A,initially found in differentglnBstrains, are indeed suppressor mutations. When these mutations were reconstructed in the wild-type background, theglnBgene could be efficiently inactivated. Furthermore, the point mutations have different effects on PipX levels, coactivation of NtcA-dependent genes and protein–protein interactions. Further support for anin vivorole of PipX–PIIcomplexes is provided by interaction analysis with thein vivo-generated PIIT-loop+7protein, a PIIderivative unable to interact with its regulatory targetN-acetyl-l-glutamate kinase, but which retains the ability to bind to PipX. The implications of these results are discussed.
ATRX interacts with H3.3 in maintaining telomere structural integrity in pluripotent embryonic stem cells
Authors: Wong Lee H. , McGhie James D. , Sim Marcus , Anderson Melissa A. , Ahn Soyeon , Hannan Ross D. , George Amee J. , Morgan Kylie A. , Mann Jeffrey R. , Choo K.H. Andy
Published: January 2010

ATRX (alpha thalassemia/mental retardation syndrome X-linked) belongs to the SWI2/SNF2 family of chromatin remodeling proteins. Besides the ATPase/helicase domain at its C terminus, it contains a PHD-like zinc finger at the N terminus. Mutations in the ATRX gene are associated with X-linked mental retardation (XLMR) often accompanied by alpha thalassemia (ATRX syndrome). Although ATRX has been postulated to be a transcriptional regulator, its precise roles remain undefined. We demonstrate ATRX localization at the telomeres in interphase mouse embryonic stem (ES) cells in synchrony with the incorporation of H3.3 during telomere replication at S phase. Moreover, we found that chromobox homolog 5 (CBX5) (also known as heterochromatin protein 1 alpha, or HP1 alpha) is also present at the telomeres in ES cells. We show by coimmunoprecipitation that this localization is dependent on the association of ATRX with histone H3.3, and that mutating the K4 residue of H3.3 significantly diminishes ATRX and H3.3 interaction. RNAi-knockdown of ATRX induces a telomere-dysfunction phenotype and significantly reduces CBX5 enrichment at the telomeres. These findings suggest a novel function of ATRX, working in conjunction with H3.3 and CBX5, as a key regulator of ES-cell telomere chromatin.
Treatment of patients with cocaine‐induced arrhythmias: bringing the bench to the bedside
Authors: Hoffman Robert S.
Published: January 2010

Widespread use of cocaine and its attendant toxicity has produced a wealth of benchwork studies and small animal investigations that evaluated the effects of cocaine on the cardiovascular system. Despite this wealth of knowledge, very little is known about the frequency or types of arrhythmias in patients with significant cocaine toxicity. The likely aetiologies; catecholamine excess, sodium channel blockade, potassium channel blockade, calcium channel effects, or ischaemia may act alone or in concert to produce a vast array of clinical findings that are modulated by hyperthermia, acidosis, hypoxia and electrolyte abnormalities. The initial paper in the series by Wood & Dargan providing the epidemiological framework of cocaine use and abuse is followed by a detailed review of the electrophysiological effects of cocaine by O'Leary & Hancox. This review is designed to complement the previous papers and focuses on the diagnosis and treatment of patients with cocaine‐associated arrhythmias.
Micro‐particle‐induced X‐ray emission mapping of elemental distribution in roots of a Mediterranean‐type sclerophyll,Agathosma betulina(Berg.) Pillans, colonized byCryptococcus laurentii
Authors: CLOETE KAREN J. , PRZYBYLOWICZ WOJCIECH J. , MESJASZ‐PRZYBYLOWICZ JOLANTA , BARNABAS ALBAN D. , VALENTINE ALEXANDER J. , BOTHA ALFRED
Published: January 2010

The role of rhizosphere yeasts as plant nutrient‐scavenging microsymbionts in resource‐limited Mediterranean‐type heathlands is unknown. This study, therefore, focused on quantitative elemental distribution within the roots of a medicinal sclerophyll,Agathosma betulina(Berg.) Pillans, grown under nutrient‐poor conditions, and colonized byCryptococcus laurentii. Micro‐particle‐induced X‐ray emission (PIXE) was used to assess quantitative elemental distribution within the roots ofA. betulinainoculated with viableC. laurentii, as well as within roots of control plants that received autoclaved yeast. To aid in the interpretation of heterogeneous elemental distribution patterns, apoplastic barriers (Casparian bands) in root tissues were located using fluorescence microscopy. In addition, root cross‐sections were examined for endophyticC. laurentiiusing light and transmission electron microscopy (TEM). The average concentrations of P, Fe and Mn were significantly (P < 0.05) higher in roots of yeast‐inoculated plants, compared to control plants. Casparian bands were observed in the exodermal cells of both treatments, and the presence of these bands was correlated with elemental enrichment in the epi/exodermal‐outer cortical tissues. Light and TEM micrographs revealed that the yeast was not a root endophyte. This is the first report describing the role of a soil yeast as a plant nutrient‐scavenging microsymbiont.
Regulation by light of ammonium transport systems in Chlamydomonas reinhardtii
Authors: ERMILOVA ELENA V. , ZALUTSKAYA ZHANNETA M. , NIKITIN MAXIM M. , LAPINA TATYANA V. , FERNÁNDEZ EMILIO
Published: January 2010

The unicellular green alga Chlamydomonas reinhardtii is able to take up methylammonium/ammonium from the medium at different stages of its sexual life cycle. Vegetative cells and pre‐gametes mostly used a low‐affinity system (LATS) component, but gametes obtained after light treatment of N‐deprived pre‐gametes expressed both LATS and high‐affinity system (HATS) components for the uptake of methylammonium/ammonium. The activity of the LATS component was stimulated by light in only 5 min in a process independent of protein synthesis. By using the lrg6 mutant that produces sexually competent gametes in the dark, light effects on ammonium transport and gamete differentiation have been separately analysed. We have found light regulation of four Amt1 genes: Amt1; 1, Amt1; 2, Amt1; 4 and Amt1; 5. Whereas light‐dependent expression of Amt1; 1, Amt1; 2 and Amt1; 4 was independent of gametogenesis, and that of Amt1; 5 was activated in the lrg6 mutant, suggesting a connection between this transporter and the subsequent events taking place during gametogenesis.
Occult hepatitis B virus infection in patients with chronic hepatitis C: An actor behind the scene or just a bystander?
Authors: Chu Chi‐Jen , Lee Shou‐Dong
Published: January 2010

See article in J. Gastroenterol. Hepatol. 2010; 25: 259–263
Does non‐alcoholic fatty liver disease predispose patients to type 2 diabetes in the absence of obesity?
Authors: Fan Jian‐Gao , Farrell Geoffrey C
Published: January 2010

See article in J. Gastroenterol. Hepatol. 2010; 25: 352–356
Prognostic significance of survivin‐expressing circulating tumour cells in T1G3 bladder cancer
Authors: Gradilone Angela , Petracca Arianna , Nicolazzo Chiara , Gianni Walter , Cortesi Enrico , Naso Giuseppe , Vincenzi Bruno , Cristini Cristiano , De Berardinis Ettore , Di Silverio Franco , Aglianò Anna Maria , Gazzaniga Paola
Published: January 2010

OBJECTIVE

To evaluate the prognostic significance of survivin in tumour tissues and that of survivin‐expressing circulating tumour cells (CTCs) in T1G3 bladder tumours, as the prognosis of T1G3 bladder cancer is highly variable and unpredictable from clinical and pathological prognostic factors.

PATIENTS AND METHODS

The study included 54 patients with T1G3 non‐muscle‐invasive bladder cancer. Additional inclusion criteria were: tumour size <3 cm, absence of carcinoma in situ and multifocality. The planned follow‐up was 24 months. Survivin was evaluated by reverse transcription‐polymerase chain reaction in tumour tissues. CTCs were isolated from blood by CELLectionTM Dynabeads (Invitrogen, Carlsbad, CA, USA) coated with the monoclonal antibody towards the human epithelial cell adhesion molecule. Cells were lysed and Dynabeads Oligo(dT) was used to capture poly A + mRNA. cDNA was synthesized and analysed for the expression of CD45, CK8 and survivin. The primary endpoint was disease‐free survival (DFS); the favourable group at 24 months was defined as that with no clinical evidence of disease; the unfavourable group was that with evidence of recurrent disease or progressive disease. Tumour survivin expression and presence of CTC were correlated with DFS. Multivariate analysis was used to investigate whether the presence of CTC was an independent indicator of DFS.

RESULTS

Survivin was found in half of the tumours; patients with survivin‐negative tumours had a longer DFS than those with survivin‐positive tumours (chi‐square, P = 0.029). CTCs were found in 24/54 patients (44%); 92% of CTC expressed survivin. The difference in DFS between CTC–ve and CTC+ve patients was statistically significant (chi‐square, P < 0.001). The presence of CTC was an independent prognostic factor for DFS (P < 0.001).

CONCLUSION

The presence of CTC is an independent prognostic factor in patients with T1G3 bladder cancer.
Prognostic significance of a positive surgical margin in pathologically organ‐confined prostate cancer
Authors: Ahyai Sascha A. , Zacharias Mario , Isbarn Hendrik , Steuber Thomas , Eichelberg Christian , Köllermann Jens , Fisch Margit , Karakiewicz Pierre I. , Huland Hartwig , Graefen Markus , Chun Felix K.‐H.
Published: January 2010

Study Type – Therapy (case series) Level of Evidence 4

OBJECTIVE

To identify risk factors of a positive surgical margin (PSM) and the significance of a PSM after radical prostatectomy (RP) on biochemical recurrence (BCR) in exclusively pathologically confirmed organ‐confined (OC) prostate cancer, as despite an excellent prognosis after RP, some patients with pathologically confirmed OC disease have BCR, and the prognostic significance of a PSM in these men remains unclear.

PATIENTS AND METHODS

We assessed 932 men with pathologically OC disease who were treated with RP by nine different surgeons between 1992 and 2004. The prognostic significance of clinical and pathological variables, including tumour volume (TV) and percentage of high‐grade TV (%HGTV) were assessed. Logistic and Cox regression models were fitted to identify risk factors of a PSM and BCR. BCR was defined as a prostate‐specific antigen (PSA) level of 0.1 ng/mL and increasing after an undetectable PSA level.

RESULTS

The total PSM rate was 12.9% (120 men); the mean TV (P < 0.001), but not %HGTV (P= 0.2) was significantly higher in patients with PSM. TV, nerve‐sparing RP technique and surgical volume were independent risk factors for a PSM (P= 0.03). After a median follow‐up of 35 months the overall BCR rate was 8.8% (82 men). Patients with a PSM had significantly higher BCR rates (21.7% vs 6.9%; P < 0.001). In univariable analysis, a high %HGTV (70.4%) was the most informative risk factor of BCR, followed by RP Gleason score (65.8%) and PSM (65.7%). Removal of PSM from a multivariable Cox model decreased the accuracy by 12.1% (P < 0.001).

CONCLUSIONS

Our findings show that in OC prostate cancer, the risk of a PSM depends on TV, surgical technique and surgical volume. PSM is a significant risk factor for BCR. However, only 20% men with OC disease and a PSM develop BCR; conversely, 80% of men are cured despite a PSM. Therefore, adjuvant therapy must be considered, with caution to avoid unnecessary overtreatment.
Face, content and construct validation of the first virtual reality laparoscopic nephrectomy simulator
Authors: Brewin James , Nedas Tim , Challacombe Ben , Elhage Oussama , Keisu Jonas , Dasgupta Prokar
Published: January 2010

Study Type – Therapy (case series) Level of Evidence 4

OBJECTIVE

To evaluate the face, content and construct validity, and to identify whether participants improved with practice, for the Procedicus MIST Nephrectomy™ simulator (Mentice, Gothenburg, Sweden), which incorporates force feedback and can record numerous performance measures (metrics) during the simulation, and which is the first virtual reality simulator for laparoscopic nephrectomy.

SUBJECTS AND METHODS

Eight expert urological laparoscopic surgeons, 10 novices and 10 trainee urologists completed at least one simulated retroperitoneal radical nephrectomy. They completed a structured questionnaire to assess face and content validity; the performance of experts and novices were then compared to evaluate construct validity.

RESULTS

Face validity was established by the experts who all felt the simulator was a good training tool. Content validity was established by the experts who rated all aspects of the simulator as above average for realism. When performance metrics were analysed, experts completed the simulated nephrectomy significantly faster than novices, with fewer errors, less simulated haemorrhage and less tool travel, which established construct validity. After practice, both novices and trainees were able to perform the simulation faster, with fewer errors, less blood loss and less tool travel.

CONCLUSIONS

This study has established the face, content and construct validity for the Procedicus MIST Nephrectomy. The simulator can distinguish experts from novices and it has potential as a laparoscopic training tool for urology.
Two susceptible diabetogenic variants near/in MTNR1B are associated with fasting plasma glucose in a Han Chinese cohort
Authors: Kan M. Y. , Zhou D. Z. , Zhang D. , Zhang Z. , Chen Z. , Yang Y. F. , Guo X. Z. , Xu H. , He L. , Liu Y.
Published: January 2010

Diabet. Med. 27, 598–602 (2010)

Aims  To investigate the two variants (rs1387153 and rs10830963) near/in the melatonin receptor 1B gene (MTNR1B) and to determine their association with Type 2 diabetes, as well as with the regulation of fasting plasma glucose (FPG) in Han Chinese subjects.

Methods  The two variants were genotyped in 1912 unrelated Type 2 diabetic patients and 2041 healthy individuals. Association with Type 2 diabetes was calculated by logistic regression with adjustments for sex, age and body mass index. The possible connection between the risk alleles and FPG was analysed by multiple linear regression.

Results  The two polymorphisms were associated with FPG levels in the healthy individuals (P = 0.003 and P = 0.002, respectively), and the G allele of rs10830963 was also associated with an increased risk of Type 2 diabetes in our patient sample (odds ratio, 1.12; 95% confidence interval, 1.02–1.23; P = 0.024). Moreover, the linkage disequilibrium degree of two single nucleotide polymorphisms was high (r2 = 0.66), which is similar to that of Europeans.

Conclusions  The common variant in MTNR1B confers the risk of Type 2 diabetes and modulates FPG in both the Han Chinese and European populations.
ECONOMIC EFFECTS OF CURRENCY UNIONS
Authors: BARRO ROBERT , TENREYRO SILVANA
Published: January 2010

We develop a new instrumental‐variable (IV) approach to estimate the effects of different exchange rate regimes on bilateral outcomes. The basic idea is that the characteristics of the exchange rate between two countries are partially related to the independent decisions of these countries to peg—explicitly or de facto—to a third currency, notably that of a main anchor. This component of the exchange rate regime can be used as an IV in regressions of bilateral outcomes. We apply the methodology to study the economic effects of currency unions. The likelihood that two countries independently adopt the currency of the same anchor country is used as an instrument for whether they share a common currency. We find that sharing a common currency enhances trade, increases price comovements, and decreases the comovement of real gross domestic product shocks. (JEL C3, F3, F4)
COTTON IN A FREE TRADE WORLD
Authors: PAN SUWEN , FADIGA MOHAMADOU , MOHANTY SAMARENDU , WELCH MARK
Published: January 2010

Trade liberalizing reform in the world cotton market would increase world cotton traded an average 2.69% over 5 yr and increase world cotton prices to an average 10.5%. A partial equilibrium model was used to estimate the effects of removing global domestic subsidies and border tariffs for cotton. Trade flows in international markets would be affected as U.S. market share of world cotton exports decline, net cotton‐importing countries with minimum domestic and trade distortions import less because of higher cotton prices, and net cotton‐importing countries that subsidize domestic production and/or impose border tariffs significantly increase their imports. (JEL F17, F42, F47, O2)
CRIME AND PUNISHMENT IN MAJOR LEAGUE BASEBALL: THE CASE OF THE DESIGNATED HITTER AND HIT BATTERS
Authors: BRADBURY JOHN CHARLES , DRINEN DOUGLAS J.
Published: January 2010

Past studies have found a positive correlation between the use of the designated hitter in baseball and hit batters, but the reason for this is debatable. Using a new micro‐level data set of individual plate appearances, we control for detailed cost‐benefit attributes that affect the decision calculus of the pitcher to isolate the deterrent impact of requiring the pitcher to bat. We find that pitchers hit batters strategically, and the deterrent effect of requiring pitchers to bat explains 60%–80% of the difference in hit batsmen between leagues. We also identify evidence of direct retaliation against plunking pitchers. (JEL D81, KC42, L83)
THE SLOWDOWN IN FIRST‐RESPONSE TIMES OF ECONOMICS JOURNALS: CAN IT BE BENEFICIAL?
Authors: AZAR OFER H.
Published: January 2010

The first‐response time (henceforth FRT) of economics journals has increased over the last four decades from 2 months to 3–6 months. The optimal FRT, however, is not zero because a longer FRT deters submissions of mediocre papers to good journals and consequently saves valuable time of referees and editors. Interestingly, the change in the actual FRT is in the same direction as the change in the optimal FRT. The latter has increased because of the availability of research on the Internet prior to publication and because papers became longer and more mathematical, increasing the costs of refereeing a paper. (JEL L82, A10, A14, I23, A19)
Top Management Team Advice Seeking and Exploratory Innovation: The Moderating Role of TMT Heterogeneity
Authors: Alexiev Alexander S. , Jansen Justin J. P. , Van den Bosch Frans A. J. , Volberda Henk W.
Published: January 2010

abstract

Research on strategic decision making has considered advice‐seeking behaviour as an important top management team attribute that influences organizational outcomes. Yet, our understanding about how top management teams utilize advice to modify current strategies and pursue exploratory innovation is still unclear. To uncover the importance of advice seeking, we delineate between external and internal advice seeking and investigate their impact on exploratory innovation. We also argue that top management team heterogeneity moderates the impact of advice seeking on exploratory innovation. Findings indicated that both external and internal advice seeking are important determinants of a firm's exploratory innovation. In addition, we observed that top management team heterogeneity facilitates firms to act upon internal advice by combining different perspectives and developing new products and services. Interestingly, heterogeneous top management teams appeared to be less effective to leverage external advice and pursue exploratory innovation.
Agency Perspectives on Corporate Governance of Multinational Enterprises
Authors: Filatotchev Igor , Wright Mike
Published: January 2010

abstract

This paper argues for a greater focus on an agency theory (AT) perspective in understanding corporate governance in multinational enterprises (MNEs) since, despite recent developments, the traditional internalization theory approach limits our understanding of the behaviour of these firms. We analyse the contribution of an AT perspective to understanding various aspects of corporate governance in MNEs: internationalization, international joint ventures (IJVs), headquarters–subsidiary relationships, and new forms of global business groups. From this analysis, we suggest that even with the emerging AT literature's focus on the role of ownership as a key governance factor, there is substantial need for research on several key corporate governance mechanisms; namely, the role and nature of dominant owners, the composition of boards of directors, the separation of CEOs and board chairs, executive remuneration, and the role of the market for corporate control. There is scope to examine further the implications of different institutional environments for AT perspectives on the behaviour of MNEs.
Appetite control: methodological aspects of the evaluation of foods
Authors: Blundell J. , De Graaf C. , Hulshof T. , Jebb S. , Livingstone B. , Lluch A. , Mela D. , Salah S. , Schuring E. , Van Der Knaap H. , Westerterp M.
Published: January 2010

This report describes a set of scientific procedures used to assess the impact of foods and food ingredients on the expression of appetite (psychological and behavioural). An overarching priority has been to enable potential evaluators of health claims about foods to identify justified claims and to exclude claims that are not supported by scientific evidence for the effect cited. This priority follows precisely from the principles set down in the PASSCLAIM report. The report allows the evaluation of the strength of health claims, about the effects of foods on appetite, which can be sustained on the basis of the commonly used scientific designs and experimental procedures. The report includes different designs for assessing effects on satiation as opposed to satiety, detailed coverage of the extent to which a change in hunger can stand alone as a measure of appetite control and an extensive discussion of the statistical procedures appropriate for handling data in this field of research. Because research in this area is continually evolving, new improved methodologies may emerge over time and will need to be incorporated into the framework. One main objective of the report has been to produce guidance on good practice in carrying out appetite research, and not to set down a series of commandments that must be followed.
Option‐Adjusted Delta Credit Spreads: a Cross‐Country Analysis
Authors: Becchetti Leonardo , Carpentieri Andrea , Hasan Iftekhar
Published: January 2010

This study analyses the determinants of the variation in option‐adjusted credit spreads (OASs) using a unique database and enlarges the traditional analysis to include disaggregated indexes, new variables, and a complete set of markets (USA, UK, and the Eurozone). An extended set of regressors explains almost half the variability of OASs in the three markets. We find that institutional trading activity significantly affects corporate bond spreads, signalling either variation in perceptions of risk or the existence of an indirect measure of liquidity. We also find that US business cycle indicators significantly affect the variability of OASs in the UK and the Eurozone. Finally, we find evidence that stock returns have more influence on high‐yield bonds in the Eurozone than in the USA.
Pathways to the diagnosis of ovarian cancer in the UK: a cohort study in primary care
Authors: Barrett J , Sharp DJ , Stapley S , Stabb C , Hamilton W
Published: January 2010

Please cite this paper as: Barrett J, Sharp D, Stapley S, Stabb C, Hamilton W. Pathways to the diagnosis of ovarian cancer in the UK: a cohort study in primary care. BJOG 2010;117:610–614.

Objective  To identify the routes patients with ovarian cancer take between first symptom presentation and diagnosis.

Design  Cohort study.

Setting  The study took place in 39 general practices in Devon, UK.

Population  All ovarian cancer patients identified in the practices, with a diagnosis between 2000 and 2007 inclusive.

Methods  All patients had their cancer symptoms, referrals, and diagnoses identified and dated using their doctors’ records.

Main outcome measures  Numbers of patients taking specific routes to diagnosis, together with the time taken to diagnosis.

Results  Three main routes to diagnosis emerged. The first was the expected route of outpatient referral: 195 (92% of the total) had at least one of the seven ovarian cancer symptoms or an abdominal mass. A total of 123 (58%) were referred to a specialist, although only 65 (31%) were referred to a gynaecologist. Thirty‐five (17%) were initially investigated within primary care by ultrasound scanning, and a further 35 (17%) were admitted as emergencies. The interval from first symptom to referral was similar across the different pathways, with a median (interquartile range) time between the first symptom presenting to primary care and first investigation or referral being 2.5 (0, 27.5) days. The median interval from first symptom reported in primary care to diagnosis was 74.5 (32, 159) days.

Conclusions  Only a minority of ovarian cancer patients follow the expected route to diagnosis, of urgent referral to a gynaecologist. In most women, GPs rapidly identified the need to investigate. Avoidable delays generally occurred after the decision to investigate was made.
Decreased leg glucose uptake during exercise contributes to the hyperglycaemic effect of octreotide
Authors: Hovind Peter , Simonsen Lene , Bülow Jens
Published: January 2010

Aim:  During prolonged infusion of somatostatin, there is an increase in arterial glucose concentration, and this increase persists even during prolonged exercise. The aim of the study was to measure glucose uptake in the leg muscles during infusion of the somatostatin analogue octreotide before and during leg exercise.

Material and methods:  Eight healthy male subjects were investigated twice in the fasting state: during 3 h infusion of octreotide [30 ng (kg min)−1] or sodium chloride with exercise at 50% of maximal VO2 in the last hour. Glucose uptake and oxygen uptake in the leg were measured using Fick’s principle by blood sampling from an artery and a femoral vein. Blood flow in the leg was measured using the indicator (indocyanine green) dilution technique.

Results:  After an initial decrease during rest, octreotide infusion resulted in a significant increase in arterial glucose concentrations compared to control conditions during exercise (mean ± SEM: 7·6 ± 0·6 versus 5·6 ± 0·1 mmol l−1, P<0·01). During rest, octreotide did not change the leg glucose uptake (59 ± 10 versus 55 ± 11 μmol min−1). In contrast, leg glucose uptake was significantly lower during exercise compared to control conditions (208 ± 79 versus 423 ± 87 μmol min−1, P<0·05). During exercise, leg oxygen uptake was not different in the two experiments (20·4 ± 1·3 versus 19·5 ± 1·1 μmol min−1).

Conclusion:  In conclusion, infusion of octreotide reduced leg glucose uptake during exercise, despite the same leg oxygen consumption and blood flow compared to control conditions. The hyperglycaemic effect of octreotide can partly be explained by the reduction in leg glucose uptake. Furthermore, the results suggest that a certain level of circulating insulin is necessary to obtain sufficient stimulation of glucose uptake in the exercising muscles.
Glucagon‐like peptide 1 receptor stimulation as a means of neuroprotection
Authors: Harkavyi Alexander , Whitton Peter S.
Published: January 2010

Glucagon‐like peptide 1 (GLP‐1) is a relatively recently discovered molecule originating in the so‐called L‐cells of the intestine. The peptide has insulinotrophic properties and it is this characteristic that has predominantly been investigated. This has led to the use of the GLP‐1‐like peptide exendin‐4 (EX‐4), which has a much longer plasma half‐life than GLP‐1 itself, being used in the treatment of type II diabetes. The mode of action of this effect appears to be a reduction in pancreatic apoptosis, an increase in beta cell proliferation or both. Thus, the effects of GLP‐1 receptor stimulation are not based upon insulin replacement but an apparent repair of the pancreas. Similar data suggest that the same effects may occur in other peripheral tissues. More recently, the roles of GLP‐1 and EX‐4 have been studied in nervous tissue. As in the periphery, both peptides appear to promote cellular growth and reduce apoptosis. In models of Alzheimer's disease, Parkinson's disease and peripheral neuropathy, stimulation of the GLP‐1 receptor has proved to be highly beneficial. In the case of Parkinson's disease this effect is evident after the neurotoxic lesion is established, suggesting real potential for therapeutic use. In the present review we examine the current status of the GLP‐1 receptor and its potential as a therapeutic target.
Porcelain Fracture Resistance of Screw‐Retained, Cement‐Retained, and Screw‐Cement‐Retained Implant‐Supported Metal Ceramic Posterior Crowns
Authors: Al‐Omari Wael M. , Shadid Rola , Abu‐Naba’a Layla , Masoud Bilal El
Published: January 2010

Purpose: The purpose of this in vitro study was to compare the porcelain fracture resistance between screw‐retained, cement‐retained, and combined screw‐ and cement‐retained metal–ceramic (MC) implant‐supported posterior single crowns; and to investigate the effect of offsetting the occlusal screw‐access opening on porcelain fracture resistance of screw‐retained and cement‐retained MC implant‐supported posterior single crowns.

Materials and Methods: Forty standardized MC molar‐shaped restorations were fabricated. The 40 restorations were divided into four groups (SRC, SRO, CRP, and CSC) of 10 specimens each. Group SRC: screw‐retained, screw‐access hole placed in the center of the occlusal surface; Group SRO: screw‐retained, screw access hole placed 1 mm offset from the center of the occlusal surface toward the buccal cusp; Group CRP: cement‐retained, zinc phosphate cement was used; Group CSC: cement‐retained with a screw‐access hole in the center of the occlusal surface. The screw‐retained restorations and abutments were directly attached to 3i implant fixtures embedded in acrylic resin blocks. Subsequently, all test specimens were thermocycled and vertically loaded in a universal testing machine at a crosshead speed of 2 mm/min until fracture. Mean values of load at fracture (in N) were calculated in each group and compared with a one‐way ANOVA and Tukey's Studentized test (α= 0.05).

Results: Mean values of loads required to fracture the restorations were as follows (N): Group SRC: 1721 ± 593; Group SRO: 1885 ± 491; Group CRP: 3707 ± 1086; Group CSC: 1700 ± 526. Groups SRC, SRO, and CSC required a significantly lower force to fracture the porcelain than did the CRP group (p < 0.05).

Conclusion: The cement‐retained restorations showed significantly higher mean fracture loads than the restorations having screw‐access openings in their occlusal surface. The position of the screw‐access hole within the occlusal surface did not significantly affect the porcelain fracture resistance.
Hierarchical Porous, Self‐Supporting La‐ and F‐Codoped TiO2 with High Durability for Continuous‐Flow Visible Light Photocatalysis
Authors: Cao Guangxiu , Li Yaogang , Zhang Qinghong , Wang Hongzhi
Published: January 2010

Hierarchical porous, self‐supporting La‐ and F‐codoped TiO2 with high durability was prepared using a simple polymer template gel. The TiO2 foams were in the anatase phase, with a specific surface area of up to 88 m2/g, and showed a network‐like structure containing meso‐/macropores. The macropores had a diameter of ca. 300 nm and a wall thickness of 100–300 nm, while the mesopores were narrowly distributed with a mean diameter of around 5.4 nm. The UV‐vis diffuse reflection spectra of the sample showed that the presence of intraband gap states was likely responsible for its absorption of visible light. X‐ray photoelectron spectroscopy revealed that La2O3 and O–Ti–F bonds were formed. The sample showed an excellent visible light photocatalytic activity and a high durability of photocatalytic activity for the degradation of methylene blue solution.
Effect of the Reoxidation on Positive Temperature Coefficient Behavior of BaTiO3–Bi0.5Na0.5TiO3
Authors: Wei Jifeng , Pu Yongping , Mao Yuqin , Wang Jinfei
Published: January 2010

As a positive temperature coefficient of resistivity (PTCR) material, (1−x)BaTiO3–x(Bi0.5Na0.5)TiO3 (BT–BNT, 0.01≤x≤0.08) ceramics without any donor doping were prepared by a conventional solid‐state reaction method. All samples were sintered in an N2 atmosphere at 1340°C, followed by reoxidizing at 800°–1100°C in air. The PTCR characteristics of BT–BNT ceramics were investigated in terms of BNT content, reoxidation temperature, and time. Room‐temperature resistivity (ρRT) of simples sintered in N2 decreased to 102Ω·cm, and the jump in resistivity (maximum resistivity [ρmax]/minimum resistivity [ρmin]) was enhanced by three orders of magnitude through a suitable reoxidation process without sacrificing the ρRT. The Curie temperature (Tc) was shifted to a high temperature (>130°C) with an increase in the BNT content. With the addition of 4 mol% BNT, the obtained ceramic exhibited a low ρRT of 2 × 102Ω·cm, a typical PTC effect of ρmax/ρmin>103, and a Tc of 160°C.
Preparation and Characterization of Highly Activated MnO2 Nanostructure
Authors: Han Xiaoyan , Zhang Feng , Meng Qingfei , Sun Jutang
Published: January 2010

Highly activated MnO2 nanostructure was prepared from potassium permanganate and manganese acetate, via a simple alternate drop‐feeding method. This highly activated MnO2 could combust in the atmosphere of ethanol vapors to yield nanocrystalline Mn3O4 at 114°C. Powder X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, particle size distribution, and electrochemical tests were used to characterize the as‐obtained products. The results show that the as‐prepared MnO2 nanostructure shows good electrochemical properties.
Mechanisms and Kinetics of the Hydrothermal Oxidation of Bulk Titanium Silicon Carbide
Authors: Zhang Haibin , Presser Volker , Berthold Christoph , Nickel Klaus Georg , Wang Xin , Raisch Christoph , Chassé Thomas , He Lingfeng , Zhou Yanchun
Published: January 2010

Hydrothermal oxidation of bulk Ti3SiC2in continuous water flow was studied at 500°–700°C under a hydrostatic pressure of 35 MPa. The oxidation was weak at 500°–600°C and accelerated at 700°C due to the formation of cracks in oxides. The kinetics obeyed a linear time‐law. Due to the high solubility of silica in hydrothermal water, the resulting oxide layers only consisted of titanium oxides and carbon. Besides general oxidation, two special modes are very likely present in current experiments: (1) preferential hydrothermal oxidation of lattice planes perpendicular to thec‐axis inducing cleavage of grains and (2) uneven hydrothermal oxidation related to the occurrence of TiC and SiC impurity inclusions. Nonetheless the resistance against hydrothermal oxidation is remarkably high up to 700°C.
Redox Relaxation in Glass Melts Doped with Copper and Arsenic
Authors: Meechoowas Ekarat , Müller Matthias , Rüssel Christian
Published: January 2010

Soda–lime–silicate glasses (16Na2O–10CaO–74SiO2, in mol%) doped with copper and arsenic were studied by high‐temperature UV‐vis spectroscopy. The base glass is a model for sheet glasses. Arsenic was one of the classical fining agents and is still used as an oxidizing additive in heavy metal oxide glasses. During heating, the Cu2+ absorptivity slightly decreased up to a temperature of 470°C. At further increasing temperatures, the absorptivity decreased more notably, and after reaching a minimum at temperatures >600°C strongly increased again. At smaller heating rates, the minimum was more pronounced and was shifted to lower temperatures. This was explained by the redox reaction: 2Cu2++As3+↔2Cu++As5+. This reaction is shifted to the left during heating. At temperatures <470°C, this reaction is kinetically frozen and at temperatures >600°C, it is in equilibrium. In between, the kinetics play an important part. Rate constants of the redox reaction were determined from relaxation times. The rate constants showed an Arrhenius behavior and were inserted into a kinetic differential equation. Numerical solutions of this differential equation were in good agreement with the results from high‐temperature spectroscopy. The activation energy is 210 kJ/mol. This value is much smaller than the activation energy of viscous flow, and hence the rate‐determining step is assumed to be the diffusion of Cu2+.
Temperature‐Insensitive Large Strain of (Bi1/2Na1/2)TiO3–(Bi1/2K1/2)TiO3–(K0.5Na0.5)NbO3 Lead‐Free Piezoceramics
Authors: Seifert Klaus T. P. , Jo Wook , Rödel Jürgen
Published: January 2010

The effect of (K0.5Na0.5)NbO3 (KNN) addition on the ferroelectric behavior of (Bi1/2Na1/2)TiO3–(Bi1/2K1/2)TiO3 (BNT–BKT) lead‐free piezoceramics was investigated. Polarization and strain hysteresis loops indicate that the ferroelectric order is disrupted significantly with the addition of KNN as a replacement for BNT and the destabilization of the ferroelectric order is accompanied by an enhancement of the unipolar strain, which peaks at a value of ∼0.48% (corresponding to a large signal d33 of ∼600 pm/V) at 1 mol% KNN content. This strain was analyzed as derived from an electrostrictive effect at lower electric fields and a converse piezoelectric effect at higher electric fields. By limiting the electric driving field to exclude the contribution from the converse piezoelectric effect, a temperature‐insensitive large‐field d33 of ∼250 pm/V up to 200°C was achieved.
Synthesis and Luminescence Properties of BaMoO4:Sm3+ Phosphors
Authors: Xia Zhiguo , Chen Daimei
Published: January 2010

BaMoO4:Sm3+ phosphor system with a tetragonal structure was synthesized via a high‐temperature solid‐state method. The charge compensated behaviors, 2Ba2+→Sm3++M+, where M+ is a monovalent cation like Li+, Na+, and K+ acting as a charge compensator, were investigated in this paper. It has been found that BaMoO4:Sm3+ phosphor by doping with K+ ions show greatly enhanced reddish orange emission compared with pure BaMoO4:Sm3+ sample. Investigation on Sm3+ and K+ concentration‐dependent emission spectra indicated that Ba0.84MoO4:0.08Sm3+,0.12K+ phosphor exhibited the strongest reddish orange emission with a CIE values of x=0.55 and y=0.43. After irradiation under the 402 nm ultraviolet (UV) excitation, three emission peaks centered at 561, 598, and 642 nm corresponding to the 4G5/2 to 6HJ (J=5/2, 7/2, 9/2) emission lines of Sm3+ were obviously observed, and the lifetimes of three emissions (4G5/2→6HJ=5/2, 7/2, 9/2) have been calculated based on the measured decay curves.
Quantitative X‐ray Diffraction Analysis and Modeling of the Crystallization Process in Amorphous Si–B–C–N Polymer‐Derived Ceramics
Authors: Tavakoli Amir Hossein , Gerstel Peter , Golczewski Jerzy Andrzej , Bill Joachim
Published: January 2010

Amorphous Si–B–C–N polymer‐derived ceramics (PDCs) with 8.3 at.% of boron were synthesized by thermolysis of the boron‐modified poly(methylvinylsilazane). The isochronal crystallization process was quantitatively studied by X‐ray diffraction (XRD) measurements using variable heating rates. Crystalline structures form within the amorphous Si–B–C–N PDCs at two stages including the formation of nanocrystalline SiC (NC‐SiC) at the first stage followed by the formation of nanocrystalline Si3N4 (NC‐Si3N4) and additional NC‐SiC at the second stage. The change of the SiC crystallite size with temperature determined from the XRD analysis was used as a part of input data for the modeling. The metastable phase fraction diagrams were computed using an available model of metastable phase equilibria including amorphous and nanocrystalline phases for various modeling parameters and variable heating rates as well. The modeling performed is consistent with the experimental results to a large extent. The impact of modeling free parameters is discussed in order to explain the discrepancies observed between the experimental and computational results. The extended study of the NC‐SiC formation at the first stage of crystallization justifies that this process is not purely controlled by kinetics and proves a crucial role of the metastable phase equilibrium between the amorphous Si–C–N domains and NC‐SiC.
Phase Characteristics and Piezoelectric Properties in the Bi0.5Na0.5TiO3–BaTiO3–K0.5Na0.5NbO3 System
Authors: Zhang Shan‐Tao , Wang Lei , Chen Yan‐Feng , Kounga Alain Brice
Published: January 2010

Lead‐free 0.94Bi0.5Na0.5TiO3–(0.06−x)BaTiO3–xK0.5Na0.5NbO3 (x=0–0.06) ceramics were prepared. All these compositions have a structure close to the rhombohedral–tetragonal morphotropic phase boundary (MPB) and good electric properties at room temperature. No significant composition dependence of ferroelectric property can be established, whereas a dependence of piezoelectric properties can be observed, e.g. the piezoelectric coefficient (d33), planar coupling factor (kp), and field‐induced strain (S) increase with increasing x when x≤0.01 and then tend to decrease. The highest d33, kp, and bipolar strain are 118 pC/N, 0.29, and 0.32%, respectively, in the composition with x=0.01. The results not only indicate that BNT–BT–KNN lead‐free piezoceramics can persist in the structure close to MPB in a wide composition range but that they may also be helpful for further investigation on lead‐free piezoceramics.
Design, Preparation, and Characterization of Graded YSZ/La2Zr2O7 Thermal Barrier Coatings
Authors: Chen Hongfei , Liu Yun , Gao Yanfeng , Tao Shunyan , Luo Hongjie
Published: January 2010

Large‐area spallation and crack formation during service are big problems of plasma‐sprayed thermal barrier coatings (TBCs), owing to their weak bond strengths and high residual stresses. Functional gradient TBCs with a gradual compositional variation along the thickness direction are proposed to mitigate these problems. In this paper, a six‐layer structured TBC composed of Y2O3 partially stabilized ZrO2 (YSZ) and La2Zr2O7 (LZ), was prepared by plasma spraying with dual powder feeding ports. This coating had a gradient composition and function. Thermal conductivity of the coating was comparable with that of a single LZ coating while the coefficient of thermal expansion was nearly equal to that of YSZ single coating. The experiment was conducted to compare the thermal shock resistance of a graded coating with a conventional YSZ/LZ double‐layer system. Changes in weight and morphology of specimens before and after thermal shock tests were analyzed. Results demonstrated that the thermal shock resistance of the graded coating was superior to the double‐layer coating. Typically, a barely visible pimple‐like spallation was present on the surface of the graded coating after 21 cycles. On the other hand, obvious delamination was observed for a double‐layer coating after six to seven cycles. Special focus was also placed on a comparative investigation of stresses that are closely related to spallation via the use of numerical simulation.
Cultural Anthropology Grow at NSF
Authors: Winslow Deborah
Published: January 2010

Deborah Winslow is contributing editor of “Gateway to NSF,” the National Science Foundation column in Anthropology News.