bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Zirconium on the Densification of Reactively Hot‐Pressed Zirconium Carbide
Authors: Chakrabarti Tamoghna , Rangaraj Lingappa , Jayaram Vikram
Published: July 2014

Densification mechanisms involved during reactive hot pressing (RHP) of zirconium carbide (ZrC) have been studied.RHPhas been carried out using zirconium (Zr) and graphite (C) powders in the molar ratios 1:0.5, 1:0.67, 1:0.8, and 1:1 at 40 MPa, 800°C–1200°C for different durations. The volume fractions of phases formed, including porosity, are determined from the measured density and from Rietveld analysis. Increased densification with an increasing nonstoichiometry in carbon has been observed. Microstructural and X‐ray diffraction observations coupled with the predictions of a model based on the constitutive laws governing plastic flow of zirconium suggest that the better densification of nonstoichiometric compositions arise from the higher amount of starting Zr and also the longer duration of its availability for plastic flow duringRHP. Volume shrinkage due to reaction betweenZrandCand the gradual elimination of the soft metal phase limit the final density achievable. Based on these observations, a two‐stepRHPcarried out at 800°C and 1200°C leads to a better densification than a singleRHPat 1200°C.
Processing, Mechanical Characterization, and Alkali Resistance of SiliconBoronOxycarbide (SiBOC) Glass Fibers
Authors: Nguyen Van Lam , Proust Vanessa , Quievryn Caroline , Bernard Samuel , Miele Philippe , Soraru Gian Domenico
Published: July 2014

A borosilicate sol–gel solution is synthesized using a mixture of methyltriethoxysilane, dimethyldiethoxysilane, and boric acid. SiBOC gel fibers are produced from the as‐synthesized sol–gel solution using a spinning apparatus. Subsequently, SiBOC glass fibers are prepared through pyrolysis under argon atmosphere at 1000°C and 1200°C. Mechanical properties of the SiBOC glass fibers are studied by measuring the tensile strength and the elastic modulus. The results show a high tensile strength −1300 and 1058 MPa, and a high Young modulus −79 and 95.5 GPa, for the fibers prepared at 1000°C and 1200°C, respectively. Furthermore, alkali resistance of the SiBOC fibers is investigated by measuring the tensile strength after soaking them for 20 h in NaOH and Ca(OH)2 solutions at 100°C. For comparison, the same measurements are performed on commercial AR and E glass fibers. The SiBOC fibers show excellent alkaline resistance and perform better than commercial AR fibers. Indeed, SiBOC fibers retain 80%–90% of the initial strength after Ca(OH)2 attack.
Preceramic Polymer‐Derived SiAlON as Sintering Aid for Silicon Nitride
Authors: Parcianello Giulio , Bernardo Enrico , Colombo Paolo , Lenčéš Zoltan , Vetrecín Michal , Šajgalík Pavol , Kašiarová Monika
Published: July 2014

Two kinds of sintering additives based on the polysiloxanes or polysilazanes filled with nano‐sized powders as SiAlON precursors were tested for the densification of Si3N4‐based ceramics. The results showed that both systems can be successfully used as additives for the preparation of Si3N4 ceramics with favorable mechanical characteristics. The ceramics were sintered with 18 wt% of preceramic polymer‐based mixture, and good fracture resistance and high hardness values were obtained after sintering in optimized conditions (temperature, dwell time, nitrogen pressure). Higher densification temperatures and longer holding times were required for sintering of samples with polysilazane‐based precursors. The best toughness values were approximately 5 MPa·m0.5, while the highest hardness was about 19 GPa. The differences in mechanical properties of the prepared composites can be related to the phase composition, microstructure and different chemical bonds present in the ceramic residue generated upon pyrolysis and final densification.
Electric Fields Obviate Constrained Sintering
Authors: Jha Shikhar K. , Raj Rishi
Published: July 2014

The phenomenon of constrained sintering, where large rigid inclusions of alumina have been shown to significantly reduce the rate of sintering of titania [Bordia and Raj (1988) J. Am. Ceram. Soc. 71, 302–310], is shown to subside nearly completely during flash sintering carried out under modest electrical fields. The result is explained by a different mechanism for volumetric and shear deformation under electric fields. It is proposed that vacancy and interstitials generated within the grains migrate to grain boundaries and pores to produce both volumetric and shear strain at equal rates, since, in this way, the diffusion distance for both modes of deformation becomes the same. In conventional sintering, where transport occurs from one interface to another, the diffusion distance for shear is twice as far as for densification, which retards sintering should it become controlled by shear deformation, as seen in constrained sintering.
Phase Diagram and Enhanced Piezoelectric Response of Lead‐Free BaTiO3–CaTiO3–BaHfO3 System
Authors: Wang Dali , Jiang Zhaohua , Yang Bin , Zhang Shantao , Zhang Mingfu , Guo Feifei , Cao Wenwu
Published: July 2014

Three composition groups in the BaTiO3–CaTiO3–BaHfO3 ternary system, (1 − x)Ba(HfyTi1−y)O3–x(Ba1−zCaz)TiO3 (abbreviated as BHyT–xBCzT with x = 0–1.0, y = 0.16, z = 0.20; x = 0–1.0, y = 0.16, z = 0.30; x = 0–1.0, y = 0.20, z = 0.30, respectively), have been designed for investigating the variation of the intermediate O‐phase region and its effect on the electrical properties. The temperature‐composition phase diagram of each group has been proposed based on the X‐ray diffraction patterns and the temperature‐dependent dielectric behaviors. The enhanced piezoelectric properties are achieved in the O–T phase boundary compositions of the three groups, which are BH0.16T–0.58BC0.20T, BH0.16T–0.48BC0.30T and BH0.20T–0.53BC0.30T, respectively. Piezoelectric coefficient d33 of 448 pC/N is obtained in BH0.20T–0.53BC0.30T, which is higher than those of the other two phase boundary compositions. The O‐phase zone in BH0.20T–xBC0.30T is narrower than those in the BH0.16T–xBC0.20T and BH0.16T–xBC0.30T. In spite of its small O‐phase volume occupancy, the O‐phase plays a key role in the properties of the system. Our work confirms that the enhancement in piezoelectric properties is not only related to the O–T phase boundary near room temperature (RT), but also related to the shift of TR‐O toward RT. In addition, a quantitative relation between the phase boundary composition and atomic mole ratio of Hf to Ca (Rm) is proposed, which the Rm value corresponding to the phase boundary is about 0.58. The results clearly demonstrate that in this system high piezoelectric properties are achieved by tuning the specific Rm value. Such a work may provide new clues for designing lead‐free piezoelectric materials with enhanced piezoelectric property.
Resistive Switching Behaviors of Sol‐Gel‐Derived MgNb2O6 Thin Films on ITO/glass Substrate
Authors: Ho Yi‐Da , Chen Kung‐Rong , Huang Cheng‐Liang
Published: July 2014

In this study, transparent amorphous MgNb2O6 (MNO) films were fabricated via the sol‐gel method to form an Al/MNO/indium tin oxide/glass structure. The resistive switching (RS) behavior of the devices was investigated. From the DC voltage sweep test, the air‐annealed MNO samples exhibited stable and reproducible bipolar resistive switching (BRS) behavior; however, the samples annealed in an O2‐rich environment showed no RS property. These results suggest that the RS behavior of the MNO memory devices is highly related to the oxygen vacancy concentration and distribution within the MNO films. In addition, forming‐free unipolar resistive switching (URS) behavior was observed when the MNO films were annealed under an N2H2 atmosphere. In order to determine the origin of the BRS and URS behaviors, cross‐sectional high‐resolution transmission electron microscopy images of the MNO samples were acquired. The RS behavior of the MNO films can be ascribed to the release and recombination of electrons and oxygen vacancies.
Effect of Ferroelectric Polarization on Ionic Transport and Resistance Degradation in BaTiO3 by Phase‐Field Approach
Authors: Cao Ye , Shen Jie , Randall Clive , Chen Long‐Qing
Published: July 2014

We proposed a model to study the resistance degradation behavior of ferroelectric oxides in the presence of ferroelectric spontaneous polarization by combining the phase‐field model of ferroelectric domains and nonlinear diffusion equations for ionic/electronic transport. We took into account the nonperiodic boundary conditions for solving the electrochemical transport equations and Ginzburg–Landau equations using the Chebyshev collocation algorithm. We considered a single domain structure relative to a thin film BaTiO3 single crystal orientated to the normal of the electrode plates (Ni) in a single parallel plate capacitor configuration. The capacitor was subjected to a dc bias of 0.5 V either along the polarization direction or opposite to the polarization direction at 25°C. It is shown that the polarization bound charges at the metal/ferroelectric interface play an important role in charge carrier transport and leakage current evolution in BaTiO3 capacitor.
Telocytes in mice bone marrow: electron microscope evidence
Authors: Li Hua , Zhang Hongqi , Yang Lin , Lu Shanshan , Ge Junbo
Published: July 2014

Telocytes (TCs) are a novel type of interstitial cell of whom presence has been recently documented in many tissues and organs. However, whether TCs exists in bone marrow is still not reported. This study aims to find out TCs in mice bone marrow by using scanning electron microscope (SEM) and transmission electron microscope (TEM). SEM images showed that in mice bone marrow most of TCs have small spherical cell body (usually 4–6 μm diameter) with thin long telopodes (Tps; usually one to three). The longest Tp observed was about 70 μm, with an uneven calibre. Direct intercellular contacts exist between TCs. TEM shows mitochondria within dilations of Tps. Also, by TEM, we show the close spatial relations of Tps with blood vessels. In conclusion, this study provides ultrastructural evidence regarding the existence of TCs in mice bone marrow, in situ.
Protein profiling of human lung telocytes and microvascular endothelial cells using iTRAQ quantitative proteomics
Authors: Zheng Yonghua , Cretoiu Dragos , Yan Guoquan , Cretoiu Sanda Maria , Popescu Laurentiu M. , Fang Hao , Wang Xiangdong
Published: July 2014

Telocytes (TCs) are described as a particular type of cells of the interstitial space (www.telocytes.com). Their main characteristics are the very long telopodes with alternating podoms and podomers. Recently, we performed a comparative proteomic analysis of human lung TCs with fibroblasts, demonstrating that TCs are clearly a distinct cell type. Therefore, the present study aims to reinforce this idea by comparing lung TCs with endothelial cells (ECs), since TCs and ECs share immunopositivity for CD34. We applied isobaric tag for relative and absolute quantification (iTRAQ) combined with automated 2‐D nano‐ESI LC‐MS/MS to analyse proteins extracted from TCs and ECs in primary cell cultures. In total, 1609 proteins were identified in cell cultures. 98 proteins (the 5th day), and 82 proteins (10th day) were confidently quantified (screened by two‐sample t‐test, P < 0.05) as up‐ or down‐regulated (fold change >2). We found that in TCs there are 38 up‐regulated proteins at the 5th day and 26 up‐regulated proteins at the 10th day. Bioinformatics analysis using Panther revealed that the 38 proteins associated with TCs represented cellular functions such as intercellular communication (via vesicle mediated transport) and structure morphogenesis, being mainly cytoskeletal proteins and oxidoreductases. In addition, we found 60 up‐regulated proteins in ECs e.g.: cell surface glycoprotein MUC18 (15.54‐fold) and von Willebrand factor (5.74‐fold). The 26 up‐regulated proteins in TCs at 10th day, were also analysed and confirmed the same major cellular functions, while the 56 down‐regulated proteins confirmed again their specificity for ECs. In conclusion, we report here the first extensive comparison of proteins from TCs and ECs using a quantitative proteomics approach. Our data show that TCs are completely different from ECs. Protein expression profile showed that TCs play specific roles in intercellular communication and intercellular signalling. Moreover, they might inhibit the oxidative stress and cellular ageing and may have pro‐proliferative effects through the inhibition of apoptosis. The group of proteins identified in this study needs to be explored further for the role in pathogenesis of lung disease.
Neonatal jaundice and increased risk of attention‐deficit hyperactivity disorder: a population‐based cohort study
Authors: Wei Chang‐Ching , Chang Chun‐Hung , Lin Cheng‐Li , Chang Shih‐Ni , Li Tsai‐Chung , Kao Chia‐Hung
Published: July 2014

Background

Previous studies have posited conflicting results regarding the relationship between neonatal jaundice and the subsequent risk of attention‐deficit hyperactivity disorder (ADHD). We therefore performed a large population study with a defined neonatal jaundice cohort to investigate the incidence and risk of physician‐diagnosed ADHD in Taiwan.

Methods

From 2000 to 2004, 24,950 neonatal jaundice cases and 69,964 matched nonjaundice controls were identified. At the end of 2008, the incidence rate and hazard ratios (HRs) of physician‐diagnosed ADHD were calculated.

Results

The incidence of ADHD was 2.48‐fold greater in the jaundice cohort than in the nonjaundice cohort (3.84 vs. 1.51 per 100,000 person‐years) in the study period. The HR of ADHD was substantially greater for male, preterm, and low‐birth‐weight infants with neonatal jaundice. The risk of developing ADHD in the jaundice cohort was greater after a diagnosis of neonatal jaundice for more than 6 years (HR: 2.64; 95% confidence interval: 2.13–3.28). The risk of ADHD increased for neonates with higher serum bilirubin levels requiring phototherapy and with longer admission days.

Conclusion

Neonates with jaundice are at high risk for developing physician‐diagnosed ADHD during their growth period. A risk alert regarding neurologic consequences is urgently required after a neonatal jaundice diagnosis. Additional studies should be conducted to clarify the pathogenesis of these relationships.
Partner switching can favour cooperation in a biological market
Authors: Schwagmeyer P. L.
Published: July 2014

Intraspecific cooperation and interspecific mutualisms can be promoted by mechanisms that reduce the frequency with which cooperative organisms are exploited by unhelpful partners. One such mechanism consists of changing partners after interacting with an uncooperative individual. I used McNamaraet al.'s (Nature, 451, 2008, 189) partner switching model as a framework to examine whether this mechanism can select for increased cooperative investment by house sparrows (Passer domesticus) collaborating to rear offspring; previous research on this species has shown that substantial cooperative investments by both pair members are required to achieve high pay‐offs from collaborating. I found that the poorer the outcome of a breeding attempt relative to the number of eggs the female invested, the greater the likelihood of partner switching. The incidence of partner switching changed seasonally, with peak switching coinciding with an increase in the number of alternative partners available to females. After females switched partners, their breeding outcomes rose to match those of females that remained with the same partner; this was not the case for males that switched partners. Consistent with the model's prediction, males in stable partnerships achieved over 25% higher than average reproductive success, which was attributable to both persistently good breeding outcomes and their older partners' high fecundity. These results provide empirical support for the hypothesis that partner switching favours increased cooperative investment levels, and they demonstrate that variation in the relative value of by‐product benefits can enhance that process.
Biology and field host range of Ceutorhynchus cardariae, a potential biological control agent for Lepidium draba
Authors: Hinz H. L. , Diaconu A.
Published: July 2014

Lepidium draba (Brassicaceae) is a clonal herb, originating from Eurasia, which is invasive in North America. A classical biological control project was initiated in 2001, and the gall‐forming weevil Ceutorhynchus cardariae was prioritized as a candidate agent. We studied its biology and field host range between 2003 and 2014 in the laboratory and a common garden in Switzerland and in the field in Romania. Ceutorhynchus cardariae is a univoltine to bivoltine species. In Switzerland, oviposition usually started at the beginning of March and can occur at temperatures as low as 2.5°C. Galls are formed on stems, leaf stalks and midribs of L. draba rosettes and bolting plants. Gall size increased with an increasing number of larvae per gall. The three larval instars feed inside the galls and leave the plant to pupate in the soil once mature. In Switzerland, development from egg to adult took about 12 weeks in spring. Adults emerged from May to July. After a brief feeding period, adults aestivate. From late summer, feeding recommenced and females may oviposit, forming a partial second generation. Eggs and all larval instars can be found in galls throughout winter. The rate of larval ectoparasitism reached 78%, while endoparasitism was low with a maximum of 2.3%. Lepidium draba populations differed in their suitability for development (number of C. cardariae produced), indicating that effectiveness of C. cardariae – in case released – may be variable. In the field, we observed that gall formation by C. cardariae can severely stunt or even kill shoots. Investigations on the field host range of C. cardariae indicated that only the closely related Lepidium campestre may act as an alternative host for the weevil in Europe. Host‐specificity tests are underway to determine its environmental safety before field release in North America is being considered.
Enhanced antiviral treatment efficacy and uptake in preventing the rising burden of hepatitis C‐related liver disease and costs in Australia
Authors: Sievert William , Razavi Homie , Estes Chris , Thompson Alexander J , Zekry Amany , Roberts Stuart K , Dore Gregory J
Published: July 2014

Background and Aim

Chronic hepatitis C virus (HCV) infection is an important cause of advanced liver disease and liver‐related deaths in Australia. Our aim was to describe the burden of HCV infection and consider treatment strategies to reduce HCV‐related morbidity and mortality.

Methods

Baseline model parameters were based upon literature review and expert consensus with a focus on Australian data. Three treatment scenarios based on anticipated introduction of improved direct‐acting antiviral regimens were considered to reduce HCV disease burden. Scenario 1 evaluated the impact of increased treatment efficacy alone (to 80–90% by 2016). Scenario 2 evaluated increased efficacy and increased treatment uptake (2550 to 13 500 by 2018) without treatment restriction, while Scenario 3 considered the same increases with treatment limited to ≥ F3 during 2015–2017.

Results

In 2013, there were an estimated 233 490 people with chronic HCV infection: 13 850 with cirrhosis, 590 with hepatocellular carcinoma (HCC) and 530 liver‐related deaths. If the current HCV treatment setting is unchanged, threefold increases in the number of people with cirrhosis, HCC, and liver disease deaths will be seen by 2030. Scenario 1 resulted in modest impacts on disease burden (4% decrease in HCC, decompensated cirrhosis, and liver deaths) and costs. Scenario 3 had the greatest impact on disease burden (approximately 50% decrease in HCC, decompensated cirrhosis, and liver deaths) and costs, while Scenario 2 had slightly lesser impact.

Conclusions

Considerable increases in the burden of HCV‐related advanced liver disease and its complications will be seen in Australia under current treatment levels and outcomes. Introduction of improved direct‐acting antiviral regimens with enhanced efficacy at current treatment levels will lead to limited impacts on this disease burden. A combination of increased treatment efficacy and greater uptake is required to achieve major reductions in advanced liver disease and related costs.
Nominal Stability and Financial Globalization
Authors: DEVEREUX MICHAEL B. , SENAY OZGE , SUTHERLAND ALAN
Published: July 2014

Over the past four decades, there has been a substantial increase in financial globalization, that is, rapid growth in gross external portfolio positions. There has also been a substantial fall in the variability of inflation. Many economists have conjectured that financial globalization contributed to the improved inflation performance. This paper explores the causal link running in the opposite direction. Using an open economy model with endogenous portfolio choice, it is shown that a monetary rule that reduces inflation variability tends to increase the size of gross external asset positions. This result appears to be robust across different modeling specifications.
The Response of Equity Prices to Movements in Long‐Term Interest Rates Associated with Monetary Policy Statements: Before and After the Zero Lower Bound
Authors: KILEY MICHAEL T.
Published: July 2014

Monetary policy actions since 2008 have influenced long‐term interest rates through forward guidance and quantitative easing. I propose a strategy to identify the comovement between interest rate and equity price movements induced by monetary policy when an observable representing policy changes is not available. A decline in long‐term interest rates induced by monetary policy statements has a larger positive effect on equity prices prior to 2009 than in the subsequent period. This change appears to reflect the impact of the zero lower bound on short‐term interest rates.
Bond Pricing with a Time‐Varying Price of Risk in an Estimated Medium‐Scale Bayesian DSGE Model
Authors: DEW‐BECKER IAN
Published: July 2014

New Keynesian model in which households have Epstein–Zin preferences with time‐varying risk aversion and the central bank has a time‐varying inflation target can match the dynamics of nominal bond prices in the U.S. economy well. The model generates a large steady‐state term spread and its fitting errors for bond yields are comparable to those obtained from a nonstructural three‐factor model, and one‐third smaller than in models with a constant inflation target or risk aversion. Including data on interest rates has large effects on variance decompositions, making investment technology shocks much less important than found in other recent papers.
Bank Panics, Government Guarantees, and the Long‐Run Size of the Financial Sector: Evidence from Free‐Banking America
Authors: CHABOT BENJAMIN , MOUL CHARLES C.
Published: July 2014

Governments attempt to increase the confidence of financial market participants by making implicit or explicit guarantees of uncertain credibility. Confidence in these guarantees presumably alters the size of the financial sector, but observing the long‐run consequences of failed guarantees is difficult. We look to America's free‐banking era and compare the consequences of a broken guarantee during the Indiana‐centered Panic of 1854 to the Panic of 1857 in which guarantees were honored. Our estimates of a model of endogenous market structure indicate substantial negative long‐run consequences to financial depth when panics cast doubt upon a government's ability to honor its guarantees.
Asset Returns and Labor Supply in a Production Economy
Authors: JACCARD IVAN
Published: July 2014

The introduction of an endogenous labor decision represents a challenge for models that seek to jointly explain asset pricing and business cycle facts. This paper shows that several improvements can be made if a standard real business cycle model is augmented with a novel preference specification that increases the stochastic discount factor volatility and simultaneously reduces the wealth elasticity of labor supply.
Addition of docosahexaenoic acid, but not arachidonic acid, activates glutathione and thioredoxin antioxidant systems in murine hippocampal HT22 cells: potential implications in neuroprotection
Authors: Casañas‐Sánchez Verónica , Pérez José A. , Fabelo Noemí , Herrera‐Herrera Antonio V. , Fernández Cecilia , Marín Raquel , González‐Montelongo María C. , Díaz Mario
Published: July 2014

Docosahexaenoic acid (DHA, 22:6n‐3) is a major constituent of nerve cell membrane phospholipids. Besides a role in membrane architecture, DHA is a pleiotropic molecule involved in multiple facets of neuronal biology and also in neuroprotection. We show here that supplementation with DHA (but not arachidonic acid) to mouse hippocampal HT22 cells modulates the expression of genes encoding for antioxidant proteins associated with thioredoxin/peroxiredoxin and glutathione/glutaredoxin systems. Thus, within the thioredoxin system, DHA increased Txn1‐2, Trxrd1‐2, Prdx3, and Srxn1 gene expression. Paralleling these changes, DHA increased thioredoxin reductase activity, the main enzyme involved in thioredoxin regeneration. For the glutathione system, the most important change triggered by DHA was the upregulation of Gpx4 gene, encoding for the nuclear, cytosolic and mitochondrial isoforms of phospholipid‐hydroperoxide glutathione peroxidase (PH‐GPx/GPx4, the main enzyme protecting cell membranes against lipid peroxidation), which was followed by a significant increase in total glutathione peroxidase and GPx4 activities. Noticeably, DHA also upregulated a new Gpx4 splicing variant that retained part of the first intronic region. Finally, we demonstrate that DHA treatment, under the same time course, protects HT22 cells from the oxitoxic exposure to amyloid beta (Aβ25–35) peptide. Altogether, our data pinpoint to a role of DHA as Indirect Antioxidant that modulates neuronal defences in neuroprotection.

image

DHA improves the antioxidant capacity of cultured hippocampal HT22 cells. We propose that DHA supplementation induces the remodelling of membrane phospholipids, and also triggers a transcriptional program to increase the expression of members of the glutathione and thioredoxin systems. We postulate that this transcriptional effect is mediated by a signal arising from non‐enzymatic oxidation of DHA.
Multiple sphingolipid abnormalities following cerebral microendothelial hypoxia
Authors: Testai Fernando D. , Kilkus John P. , Berdyshev Evgeny , Gorshkova Irina , Natarajan Viswanathan , Dawson Glyn
Published: July 2014

Hypoxia has been previously shown to inhibit the dihydroceramide (DHC) desaturase, leading to the accumulation of DHC. In this study, we used metabolic labeling with [3H]‐palmitate, HPLC/MS/MS analysis, and specific inhibitors to show numerous sphingolipid changes after oxygen deprivation in cerebral microendothelial cells. The increased DHC, particularly long‐chain forms, was observed in both whole cells and detergent‐resistant membranes. This was reversed by reoxygenation and blocked by the de novo sphingolipid synthesis inhibitor myriocin, but not by the neutral sphingomyelinase inhibitor GW‐4869. Furthermore, oxygen deprivation of microendothelial cells increased levels of dihydro‐sphingosine (DH‐Sph), DH‐sphingosine1‐phosphate (DH‐S1P), DH‐sphingomyelin (DH‐SM), DH‐glucosylceramide (DH‐GlcCer), and S1P levels. In vitro assays revealed no changes in the activity of sphingomyelinases or sphingomyelin synthase, but resulted in reduced S1P lyase activity and 40% increase in glucosylceramide synthase (GCS) activity, which was reversed by reoxygenation. Inhibition of the de novo sphingolipid pathway (myriocin) or GCS (EtPoD4) induced endothelial barrier dysfunction and increased caspase 3‐mediated cell death in response to hypoxia. Our findings suggest that hypoxia induces synthesis of S1P and multiple dihydro‐sphingolipids, including DHC, DH‐SM, DH‐GlcCer, DH‐Sph and DH‐S1P, which may be involved in ameliorating the effects of stroke
.

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Progressive hypoxia leads to the accumulation of several dihydrosphingolipids in cerebral microendothelial cells. Hypoxia also increases sphingosine‐1‐phosphate and the activity of glucosylceramide (Glc‐Cer) synthase. These changes reverse by inhibiting the de novo sphingolipid synthesis, which worsens hypoxia‐induced endothelial barrier dysfunction and apoptosis, suggesting that the identified sphingolipids may be vasculoprotective.
In Search of Neural Endophenotypes of Postpartum Psychopathology and Disrupted Maternal Caregiving
Authors: Moses‐Kolko E. L. , Horner M. S. , Phillips M. L. , Hipwell A. E. , Swain J. E.
Published: July 2014

This is a selective review that provides the context for the study of perinatal affective disorder mechanisms and outlines directions for future research. We integrate existing literature along neural networks of interest for affective disorders and maternal caregiving: (i) the salience/fear network; (ii) the executive network; (iii) the reward/social attachment network; and (iv) the default mode network. Extant salience/fear network research reveals disparate responses and corticolimbic coupling to various stimuli based upon a predominantly depressive versus anxious (post‐traumatic stress disorder) clinical phenotype. Executive network and default mode connectivity abnormalities have been described in postpartum depression (PPD), although studies are very limited in these domains. Reward/social attachment studies confirm a robust ventral striatal response to infant stimuli, including cry and happy infant faces, which is diminished in depressed, insecurely attached and substance‐using mothers. The adverse parenting experiences received and the attachment insecurity of current mothers are factors that are associated with a diminution in infant stimulus‐related neural activity similar to that in PPD, and raise the need for additional studies that integrate mood and attachment concepts in larger study samples. Several studies examining functional connectivity in resting state and emotional activation functional magnetic resonance imaging paradigms have revealed attenuated corticolimbic connectivity, which remains an important outcome that requires dissection with increasing precision to better define neural treatment targets. Methodological progress is expected in the coming years in terms of refining clinical phenotypes of interest and experimental paradigms, as well as enlarging samples to facilitate the examination of multiple constructs. Functional imaging promises to determine neural mechanisms underlying maternal psychopathology and impaired caregiving, such that earlier and more precise detection of abnormalities will be possible. Ultimately, the discovery of such mechanisms will promote the refinement of treatment approaches toward maternal affective disturbance, parenting behaviours and the augmentation of parenting resiliency.
Preoptic Inputs and Mechanisms that Regulate Maternal Responsiveness
Authors: Dobolyi A. , Grattan D. R. , Stolzenberg D. S.
Published: July 2014

The preoptic area is a well‐established centre for the control of maternal behaviour. An intact medial preoptic area (mPOA) is required for maternal responsiveness because lesion of the area abolishes maternal behaviours. Although hormonal changes in the peripartum period contribute to the initiation of maternal responsiveness, inputs from pups are required for its maintenance. Neurones are activated in different parts of the mPOA in response to pup exposure. In the present review, we summarise the potential inputs to the mPOA of rodent dams from the litter that can activate mPOA neurones. The roles of potential indirect effects through increased prolactin levels, as well as neuronal inputs to the preoptic area, are described. Recent results on the pathway mediating the effects of suckling to the mPOA suggest that neurones containing the neuropeptide tuberoinfundibular peptide of 39 residues in the posterior thalamus are candidates for conveying the suckling information to the mPOA. Although the molecular mechanism through which these inputs alter mPOA neurones to support the maintenance of maternal responding is not yet known, altered gene expression is a likely candidate. Here, we summarise gene expression changes in the mPOA that have been linked to maternal behaviour and explore the idea that chromatin remodelling during mother–infant interactions mediates the long‐term alterations in gene expression that sustain maternal responding.
Association of periodontal status with occlusal force and food acceptability in 70‐year‐old adults: from SONIC Study
Authors: Okada T. , Ikebe K. , Inomata C. , Takeshita H. , Uota M. , Mihara Y. , Matsuda K. , Kitamura M. , Murakami S. , Gondo Y. , Kamide K. , Masui Y. , Takahashi R. , Arai Y. , Maeda Y.
Published: July 2014

This cross‐sectional study aimed to investigate the association of periodontal status with occlusal force and food acceptability. We hypothesised that mastication deteriorated with reduced periodontal support, even when posterior occlusal contacts with natural teeth were maintained and the patients remained clinically asymptomatic. Participants were 482 independently living 69‐71‐year‐olds, classified as Eichner's group A, having no mobile teeth and no periodontal symptoms. The periodontal probing depth (PPD) and restoration status of each tooth were examined. Occlusal force in the intercuspal position was measured with pressure‐sensitive films. Food acceptability was evaluated from the difficulty experienced in chewing apples, grilled beef, and hard rice crackers. Multivariate regression analysis was performed to investigate the association of periodontal status with occlusal force and food acceptability. A P‐value of <0·05 was considered statistically significant. Multiple linear regression analysis showed that occlusal force had significant negative associations with maximal PPD (standardised partial regression coefficient (β) = −0·121) after controlling for gender, handgrip strength, number of teeth, and percentage of restored teeth. Approximately 15% of participants were included in the compromised food acceptability group. Logistic regression analyses showed that compromised food acceptability was significantly associated with PPD, after controlling for gender, number of teeth, and percentage of restored teeth. Periodontal probing depth (PPD) was significantly correlated with occlusal force and self‐rated food acceptability after controlling for the possible confounding factors in septuagenarians, even those with complete posterior occlusal contacts and no tooth mobility.
Podoplanin, E‐cadherin, β‐catenin, and CD44v6 in recurrent ameloblastoma: their distribution patterns and relevance
Authors: Siar Chong Huat , Ishak Ismadi , Ng Kok Han
Published: July 2014

Background

Ameloblastoma is a benign but locally infiltrative odontogenic epithelial neoplasm with a high risk for recurrence. Podoplanin, a lymphatic endothelium marker, putatively promotes collective cell migration and invasiveness in this neoplasm. However, its role in the recurrent ameloblastoma (RA) remains unclear. As morphological, signaling, and genetic differences may exist between primary and recurrent tumors, clarification of their distribution patterns is of relevance.

Materials and methods

Podoplanin was examined immunohistochemically in conjunction with E‐cadherin, β‐catenin, and CD44v6 in 25 RA. Immunostaining according to tumor area, cellular type, and location, and relationship of these proteins were analyzed. Findings were compared with 25 unrelated primary ameloblastomas (UPA).

Results

All four proteins were detected in RA and UPA samples. Expression rates for each protein were not significantly different between these two groups. RA demonstrated significant upregulation of podoplanin at the invasive front (P < 0.05), whereas upregulation of β‐catenin and CD44v6 and downregulation of E‐cadherin at this site were not statistically significant (P > 0.05). Immunolocalization for all four proteins was predominantly membranous and less frequently cytoplasmic. Pre‐ameloblast‐like cells were podoplanin+/CD44v6−, while stellate reticulum‐like cells were podoplanin‐/CD44v6+. Acanthomatous, granular cell, and desmoplastic variants in both RA and UPA were podoplanin−/low but stained weak‐to‐moderate for E‐cadherin, β‐catenin, and CD44v6. Stromal fibroblasts and lymph channels were variably podoplanin‐positive.

Conclusions

Podoplanin, β‐catenin, and CD44v6 upregulation at the tumor invasive fronts in RA and UPA supports a differential regulatory role by these molecules in mediating collective cell migration and local invasiveness. E‐cadherin downregulation suggests altered cell adhesion function during tumor progression.
Decreased expression of Kallmann syndrome 1 sequence gene (KAL1) contributes to oral squamous cell carcinoma progression and significantly correlates with poorly differentiated grade
Authors: Liu Jiannan , Cao Wei , Chen Wantao , Xu Liqun , Zhang Chenping
Published: July 2014

Background

Kallmann syndrome 1 sequence gene (KAL1) protein is an extracellular matrix associated protein which plays vital roles in neurons development and cell migration. However, its biological functions and clinical implications have yet not been revealed in oral carcinogenesis. The objective of the study was to evaluate the role of KAL1 in oral cancer and determine clinical significance of KAL1 in oral squamous cell carcinomas (OSCCs).

Methods

The expression pattern of KAL1 was examined in a testing cohort including OSCCs (n = 42) and paired adjacent tissues (PATs) (n = 14) by real‐time PCR. The result was further validated in a validating cohort of OSCCs (n = 32). Correlation between clinicopathological parameters and KAL1 mRNA levels was analyzed by Kruskal–Wallis test. In vitro, the effects of KAL1 ablation through siRNA‐mediated knockdown on the proliferation of OSCC cells were determined by CCK‐8, BrdU, and colonies formation assays, respectively. In addition, cell cycle distribution was further evaluated by cytometry.

Results

We observed that remarkably decreased expression of KAL1 mRNA in two independent cohorts (P = 0.0002 and P = 0.033, respectively). Furthermore, downregulated KAL1 mRNA was significantly associated with worse pathological grade (P = 0.013 and P = 0.035, respectively). Upon KAL1 silencing, the proliferation and colonies formation potentials of OSCC cells were notably promoted by accelerating G1 to M phase transition.

Conclusion

These data indicated that KAL1 plays a potential suppressive role on OSCC initiation and progression, and KAL1 gene may serve as an adjuvant biomarker for the identification of pathological grade.
DNA methyltransferase immunohistochemical expression in odontogenic tumours
Authors: Guimarães Douglas Magno , Antunes Daniella Moraes , Duarte Carina Magalhães Esteves , Ferro Leonardo Borges , Nunes Fabio Daumas
Published: July 2014

Background

Odontogenic tumours are a heterogeneous group of lesions formed from tissues that give rise to the tooth. DNA methylation, a covalent addition of a methyl group to the 5‐carbon position of a cytosine nucleotide, is considered an important regulator of gene expression. The addition of the methyl radical is catalysed by DNA methyltransferases (DNMTs). Although some epigenetic studies have been conducted in odontogenic tumours, a study with the three types of DNMTs in several different members of this group is missing. This study analyses the expression of DNMTs in odontogenic tumours.

Methods

Formalin‐fixed and paraffin‐embedded tissue samples of 20 ameloblastomas, 10 calcifying cystic odontogenic tumours, 10 calcifying epithelial tumours, 10 adenomatoid odontogenic tumours, 10 keratocystic odontogenic tumours, five ameloblastic fibromas, two ameloblastic fibro‐odontomas, four central odontogenic fibromas, seven peripheral odontogenic fibromas and 10 odontogenic myxomas were included. Immunohistochemical expression of DNMT1, 3A and 3B was assessed using a semi‐quantitative analysis, and also a correlation with p21, p27 and E‐cadherin immunoexpression was made.

Results

DNMT1, 3A and 3B were expressed in the nucleus and/or cytoplasm of all odontogenic tumours. DNMT1 expression was directly correlated with p27 expression in ameloblastomas.

Conclusion

The high expression of DNMTs in odontogenic tumour cells suggests methylation as an important mechanism for this group of tumours.
Potential role of hematopoietic pre‐B‐cell leukemia transcription factor‐interacting protein in oral carcinogenesis
Authors: Okada Seiji , Irié Tarou , Tanaka Junichi , Yasuhara Rika , Yamamoto Gou , Isobe Tomohide , Hokazono Chie , Tachikawa Tetsuhiko , Kohno Yohko , Mishima Kenji
Published: July 2014

Background

Hematopoietic pre‐B‐cell leukemia transcription factor‐interacting protein (HPIP) is a corepressor of pre‐B‐cell leukemia homeobox (PBX) 1 and is known to play a role in hematopoiesis. Recently, HPIP was demonstrated to promote breast cancer cell proliferation and hepatocellular carcinoma growth. Moreover, it has been revealed that homeobox and PBX proteins, the expression of which is regulated by HPIP, play key roles in cancer of various organs, including oral squamous cell carcinoma (OSCC). Nevertheless, there has not been any study regarding the role of HPIP in OSCC. This study investigated the expression of HPIP in normal oral mucosa, epithelial precursor lesion (OEPL), and OSCC, and the functional roles of HPIP in OSCC cells and normal keratinocytes.

Materials and methods

Immunohistochemical analysis of HPIP, Ki‐67, and involucrin was performed in OSCC specimens, and the change in involucrin expression following RNA interference treatment against HPIP was examined by quantitative RT‐PCR and Western blot analysis in SCC9 and NHEK cells undergoing extracellular calcium‐induced differentiation. Matrigel transwell and cell proliferation assays for both cell lines transfected with HPIP siRNA were also conducted.

Results

HPIP expression increased in OEPL and OSCC specimens. In vitro analysis revealed that HPIP suppressed differentiation and proliferation of SCC9 cells and transwell migration of NHEK cells, while HPIP promoted invasion of SCC9 and proliferation of NHEK cells. However, HPIP has no significant effect on NHEK cell differentiation.

Conclusion

HPIP may play a critical role in oral carcinogenesis and is thus a potential target for anticancer therapy, with particular emphasis on its involvement in differentiation and migration/metastasis.
Genetic variants in AKT1 gene were associated with risk and survival of OSCC in Chinese Han Population
Authors: Wang Yun , Lin Lin , Xu Hao , Li Taiwen , Zhou Yu , Dan Hongxia , Jiang Lu , Liao Ga , Zhou Min , Li Longjiang , Zeng Xin , Li Jing , Chen Qianming
Published: July 2014

Background

AKT1 is an important downstream effector of PTEN/PI3K/AKT signal transduction pathway. Aberrant expression and genetic variant of AKT1 gene are suggested to be involved in several types of human cancers, including OSCC. The aim of this study was to investigate the possible association between AKT1 gene polymorphisms and OSCC in Chinese Han Population.

Methods

A total of 182 OSCC patients and 207 cancer‐free controls were enrolled for this hospital‐based study. Five single‐nucleotide polymorphisms (SNPs) on AKT1 (rs1130214, rs1130233, rs2494732, rs3730358, rs3803300) were investigated and genotyped by Sequenom Mass ARRAY & iPLEX‐MALDI‐TOF technology. Chi‐square test, SHEsis software, and Kaplan–Meier method were used to evaluate the relationship between selected SNPs and OSCC susceptibility and progression.

Results

Significant difference of genotype distribution was observed between cases and control group at SNP sites rs1130214 (P = 0.006) and rs3803300 (P = 0.033, P = 0.003 for heterozygote and homozygous mutant, respectively). In the haplotype analysis, haplotype H4 which contained mutant‐type allele of rs1130214 and rs3803300 was also related to OSCC risk (OR = 1.974, 95% CI = 1.048–3.718). Moreover, CT genotype of rs3730358 was associated with higher risk of OSCC progression (HR = 2.466, 95% CI = 1.017–5.981).

Conclusion

Our results indicated that rs1130214 and rs3803300 were related to OSCC susceptibility in Chinese Han Population. In addition, rs3730358 might be associated with progression‐free survival time of OSCC patients, suggesting that this SNP could be a potential prognosis marker for OSCC.
Determination of Physiological Races and Evaluation of Sunflower for Resistance to Puccinia helianthi Schw
Authors: Jing Lan , Xu Xin , Jing Jiali , Li Li , Navi Shrishail S.
Published: July 2014

Sunflower rust, caused by Puccinia helianthi Schw., is a widespread disease of sunflower (Helianthus annuus L.) in China. To study physiological races, sunflower field surveys were undertaken in major sunflower growing areas of China in 2010. Forty‐four rust‐infected sunflower leaf samples were collected from 25 geographical locations. Freshly produced spores were used to study physiological race differentiation on a set of nine differentials. Race 300 was the most prevalent race observed over all locations with a 59% frequency followed by races 735, 310, 500, 724 and 737. To evaluate hybrids and varieties for resistance screening, spores of race 300 were used to inoculate 65 hybrids, and five open‐pollinated varieties selected from breeding programmes and from the seed market. None of the confection hybrids and open‐pollinated varieties was immune to race 300. Conversely, among oilseed hybrids, 3% of them showed immunity, 12% highly resistant, 59% resistant and 26% showed susceptible reactions. Open‐pollinated varieties were the most susceptible to race 300 followed by confection and oilseed sunflower hybrids. Results from this study are projected to assist breeders in selection of hybrids and varieties against prevalent race as our results showed a diversity of resistance levels to race 300.
Production rate estimation of mycosporine‐like amino acids in two Arctic melt ponds by stable isotope probing with NAH13CO3
Authors: Ha Sun‐Yong , Min Jun‐Oh , Joo Hyun Min , Chung Kyung Ho , Shin Kyung‐Hoon , Yang EunJin , Kang Sung‐Ho
Published: July 2014

The net carbon uptake rate and net production rate of mycosporine‐like amino acids (MAAs) were measured in phytoplankton from 2 different melt ponds (MPs; closed and open type pond) in the western Arctic Ocean using a 13C stable isotope tracer technique. The Research Vessel Araon visited ice‐covered western‐central basins situated at 82°N and 173°E in the summer of 2012, when Arctic sea ice declined to a record minimum. The average net carbon uptake rate of the phytoplankton in polycarbonate (PC) bottles in the closed MP was 3.24 mg C · m−3 · h−1 (SD = ±1.12 mg C · m−3 · h−1), while that in the open MP was 1.3 mg C · m−3 · h−1 (SD = ±0.05 mg C · m−3 · h−1). The net production rate of total MAAs in incubated PC bottles was highest (1.44 (SD = ±0.24) ng C · L−1 · h−1) in the open MP and lowest (0.05 (SD = ±0.003) ng C · L−1 · h−1) in the closed MP. The net production rate of shinorine and palythine in incubated PC bottles at the open MP presented significantly high values 0.76 (SD = ±0.12) ng C · L−1 · h−1and 0.53 (SD = ±0.06) ng C · L−1 · h−1. Our results showed that high net production rate of MAAs in the open MP was enhanced by a combination of osmotic and UVR stress and that in situ net production rates of individual MAA can be determined using 13C tracer in MPs in Arctic sea ice.