bluuebunny/crossref_metadata_2025_split huggingface dataset:
Expression, localization and functions in acrosome reaction and sperm motility of CaV3.1 and CaV3.2 channels in sperm cells: An evaluation from CaV3.1 and CaV3.2 deficient mice
Authors: Escoffier Jessica , Boisseau Sylvie , Serres Catherine , Chen Chien‐Chang , Kim Daesoo , Stamboulian Séverine , Shin Hee‐Sup , Campbell Kevin P. , De Waard Michel , Arnoult Christophe 
Published: April 2007

AbstractIn spermatozoa, voltage‐dependent calcium channels (VDCC) have been involved in different cellular functions like acrosome reaction (AR) and sperm motility. Multiple types of VDCC are present and their relative contribution is still a matter of debate. Based mostly on pharmacological studies, low‐voltage‐activated calcium channels (LVA‐CC), responsible of the inward current in spermatocytes, were described as essential for AR in sperm. The development of CaV3.1 or CaV3.2 null mice provided the opportunity to evaluate the involvement of such LVA‐CC in AR and sperm motility, independently of pharmacological tools. The inward current was fully abolished in spermatogenic cells from CaV3.2 deficient mice. This current is thus only due to CaV3.2 channels. We showed that CaV3.2 channels were maintained in sperm by Western‐blot and immunohistochemistry experiments. Calcium imaging experiments revealed that calcium influx in response to KCl was reduced in CaV3.2 null sperm in comparison to control cells, demonstrating that CaV3.2 channels were functional. On the other hand, no difference was noticed in calcium signaling induced by zona pellucida. Moreover, neither biochemical nor functional experiments, suggested the presence of CaV3.1 channels in sperm. Despite the CaV3.2 channels contribution in KCl‐induced calcium influx, the reproduction parameters remained intact in CaV3.2 deficient mice. These data demonstrate that in sperm, besides CaV3.2 channels, other types of VDCC are activated during the voltage‐dependent calcium influx of AR, these channels likely belonging to high‐voltage activated Ca2+channels family. The conclusion is that voltage‐dependent calcium influx during AR is due to the opening of redundant families of calcium channels. J. Cell. Physiol. 212:753–763, 2007. © 2007 Wiley‐Liss, Inc.
No evidence for vasculogenesis regulation by angiostatin during mouse embryonic stem cell differentiation
Authors: Prandini Marie‐Hélène , Desroches‐Castan Agnès , Feraud Olivier , Vittet Daniel 
Published: April 2007

AbstractDuring embryogenesis, the formation of blood vessels proceeds by both vasculogenesis and angiogenesis. Both processes appear to be finely regulated. To date, factors and genes involved in the negative regulation of embryonic vasculogenesis remain largely unknown. Angiostatin is a proteolytic fragment of plasminogen that acts as an inhibitor of angiogenesis. In this study, we analyzed the potential role of angiostatin during early stages of embryonic stem (ES) cell endothelial in vitro differentiation, as a model of vasculogenesis. We found an early expression of the known angiostatin binding sites (angiomotin, αv integrin and c‐met oncogene) during ES cell differentiation. Nevertheless, we did not detect any significant effect of angiostatin on mesoderm induction and on differentiation commitment into cells of the endothelial lineage. In both control and angiostatin‐treated conditions, the temporal and extent of formation of the Flk1 positive and Flk‐1/CD31 (PECAM‐1) positive cell populations were not significantly different. Quantitative RT‐PCR experiments of endothelial gene expression (Flk‐1, PECAM‐1 and tie‐2) confirm a lack of interference with early steps of endothelial differentiation in embryoid bodies. No evidence for an angiostatin effect on endothelial cord‐like formation could be detected at later differentiation stages. On the other hand, angiostatin inhibits vascular endothelial growth factor‐induced endothelial sprouting from embryoid bodies cultured in three dimensional type I collagen gels. Taken together, these findings support a selective inhibitory effect on the sprouting angiogenesis response for angiostatin during embryonic vascular development. J. Cell. Physiol. 213: 27–35, 2007. © 2007 Wiley‐Liss, Inc.
Separase, securin and Rad21 in neural cell growth
Authors: Pemberton H.N. , Franklyn J.A. , Boelaert K. , Chan S.Y. , Kim D.S. , Kim C. , Cheng S.Y. , Kilby M.D. , McCabe C.J. 
Published: April 2007

AbstractThe key mitotic regulator securin is expressed at low levels in fetal brain compared with adult, and modulates the proliferation of human embryonic neuronal N‐Tera2 (NT2) cells. We now examine the function and expression of securin's interacting partner separase, along with Rad21, the functional component of cohesin, which is cleaved by separase following interaction with securin. In contrast to securin, the cleaved forms of separase and Rad21 were highly expressed in human fetal cerebral cortex compared with adult. In a murine model of absent securin expression – the PTTG knock‐out mouse – separase and Rad21 were over‐expressed in multiple brain regions. In addition, cDNA array analysis of other key mitotic regulators additionally identified cyclin C and sestrin 2 to be induced in the brains of securin‐null mice compared with wild type. Further, Rad21 mRNA expression was highly correlated with that of securin, separase, cyclin C and sestrin 2 in fetal brains. In embryonic neuronal NT2 cells, siRNA repression of separase failed to significantly alter cell turnover, whereas repression of securin expression resulted in increased levels of the activated forms of Rad21 and separase, and promoted cell proliferation. Our data suggest that the co‐ordinated expression of separase, securin and Rad21 is fundamental for the developing brain. J. Cell. Physiol. 213: 45–53, 2007. © 2007 Wiley‐Liss, Inc.
Signaling pathways mediating cardiac myocyte gene expression in physiological and stress responses
Authors: Clerk Angela , Cullingford Timothy E. , Fuller Stephen J. , Giraldo Alejandro , Markou Thomais , Pikkarainen Sampsa , Sugden Peter H. 
Published: April 2007

AbstractThe contractile cells in the heart (the cardiac myocytes) are terminally differentiated. In response to pathophysiological stresses, cardiac myocytes undergo hypertrophic growth or apoptosis, responses associated with the development of cardiac pathologies. There has been much effort expended in gaining an understanding of the stimuli which promote these responses, and in identifying the intracellular signaling pathways which are activated and potentially involved. These signaling pathways presumably modulate gene and protein expression to elicit the end‐stage response. For the regulation of gene expression, the signal may traverse the cytoplasm to modulate nuclear‐localized transcription factors as occurs with the mitogen‐activated protein kinase or protein kinase B/Akt cascades. Alternatively, the signal may promote translocation of transcription factors from the cytoplasm to the nucleus as is seen with the calcineurin/NFAT and JAK/STAT systems. We present an overview of the principal signaling pathways implicated in the regulation of gene expression in cardiac myocyte pathophysiology, and summarize the current understanding of these pathways, the transcription factors they regulate and the changes in gene expression associated with the development of cardiac pathologies. Finally, we discuss how intracellular signaling and gene expression may be integrated to elicit the overall change in cellular phenotype. J. Cell. Physiol. 212: 311–322, 2007. © 2007 Wiley‐Liss, Inc.
Assessment of potential approaches to improve Eucalyptus globulus kraft pulping yield
Authors: Santiago A. S. , Neto C. Pascoal 
Published: April 2007

AbstractThe main goal of this work is to study the potential approaches to improve polysaccharides retention during Eucalyptus globulus kraft pulping. The addition of anthraquinone to kraft pulping leads to the highest pulp yield while the addition of urea promotes lower depolymerization of polysaccharides (higher pulp viscosity), but does not have a significant effect on yield. The early interruption of kraft cooking followed by oxygen delignification is a reliable approach to increase pulp yield, particularly when pulping is interrupted at the end of the faster and more selective kinetic regime (bulk phase). Yield loss during oxygen delignification is considerably lower than that incurred in the last phase of kraft pulping. Pulping with OH−/HS− charge profiling, carried out with liquor injection in three different phases leads to a yield increase. However, this increase results from a lower total alkali charge applied when profiling pulping is compared to standard pulping conditions, rather than to alkali profiling. Standard kraft pulping with different active alkali (AA) charges demonstrated that this operational variable is determinant for pulp yield and viscosity. Pulping experiences with lower AA (14%) resulted in a higher and almost constant pulp viscosity and in a higher pulp yield, assigned to improved retention of both cellulose and xylan. During the last stage of pulping, cellulose content decreases, this being mainly responsible for the decrease of pulp yield, while xylan content is almost constant, a feature attributed to the peculiar structure of this E. globulus's hemicellulose. Copyright © 2007 Society of Chemical Industry
Conventional and wet proofed CuO/Al2O3 catalysts for phenol oxidation: deactivation studies in a trickle bed reactor
Authors: Fenoglio Rosa J , Massa Paola A , Ivorra Fernando D , Haure Patricia M 
Published: April 2007

AbstractA large variety of catalytic systems have been studied for the catalytic wet air oxidation of phenolic solutions. Most of them show good activity, but serious stability problems. In this contribution, stability studies were performed over CuO/Al2O3 conventional (CNT) and polytetrafluorethylene coated (C3T) catalysts used for the oxidation of 5 g L−1 phenol solutions in a trickle bed reactor (140 °C and 7 atm of oxygen pressure). For the hydrophilic catalyst, phenol conversion decreased with usage due to the formation of Cu2O and copper oxalate phases. For the wet proofed catalyst, the hydrophobic layer prevented the appearence of those phases, and conversion levels remained practically constant with reaction time. After usage, both catalysts were oxidized at 400 °C and tested for reaction: in the case of the C3T catalyst, the phenol conversion was increased over its initial level; for CNT catalyst, the phenol conversion was also increased, but initial levels were not completely restored. The deactivation mechanism of the CNT catalyst is associated with the formation of the Cu2O and copper oxalate phases during reaction. For catalyst C3T, practically no deactivation was observed. Copyright © 2007 Society of Chemical Industry
No Eastern and Central European left behind: a cross country regression for fertility, human capital and market economy
Authors: Akin Mustafa Seref , Vlad Valerica 
Published: April 2007

AbstractIn 1999, fertility rates in Central and Eastern European countries reached the lowest levels in the world. Using panel data, this paper analyses the sharp decline in fertility for these countries during their transition towards a market economy. It extends previous research in three ways: First, it distinguishes education by gender as a proxy for human capital. Second, in addition to GDP more economic variables are used to capture the effect of a declining standard of living, including unemployment. Finally, it tries to capture the relationship between advancement toward a new market economy and fertility. Some of the results reflect some special features of the CEE region: only tertiary education is correlated with fertility; fertility is responsive to a ‘business cycle’ type of macroeconomic factors, particularly, to female unemployment; and foreign direct investment (FDI) as a proxy for new market economy has a negative association with fertility. Copyright © 2007 John Wiley & Sons, Ltd.
Improved analysis of dialkylphosphates in urine using strong anion exchange disk extraction and in‐vial derivatization
Authors: Lin Wei‐Chao , Hsieh Chang‐Yuan , Chang Ho‐Yuan 
Published: April 2007

AbstractDetermination of dialkylphosphates (DAPs) in urine is useful for assessing human exposure to organophosphates (OPs). An improved method for the determination of four DAPs based on a strong anion exchange (SAX) disk extraction and in‐vial derivatization was presented in this study. The matrix effect of urine components such as chloride ion and phosphate ion by using a SAX disk to extract DAPs in urine analysis was carefully evaluated. It was observed that the chloride ion mainly affected the extraction of diethylphosphate (DEP), dimethylthiophosphate (DMTP), and diethylthiophosphate (DETP) in urine. The addition of silver hydroxide could significantly improve the extraction efficiencies of these three DAPs, but it decreases the extraction efficiencies of dimethyldithiophosphate (DMDTP) and diethyldithiophosphate (DEDTP). The LOD of this method for DMTP, DETP, DMDTP, and DEDTP are 5, 5, 11, and 5 μg/L, respectively. A pretreatment strategy for the determination of DMTP, DMDTP, DETP, and DEDTP in urine was proposed which can provide reliable and prompt determination of routine urine analysis.
A novel solid phase for selective separation of flavonoid compounds
Authors: Xia Yong‐qing , Guo Tian‐ying , Zhao Hai‐li , Song Mou‐dao , Zhang Bang‐hua , Zhang Bao‐long 
Published: April 2007

AbstractA novel straightforward approach to selective separation for flavonoid compounds was reported. The solid phase material was prepared by copolymerization using allyl‐bromide‐modified chitosan as macromonomer, and ethylene glycol dimethacrylate as cross‐linker. The material was evaluated by chromatographic analysis; it exhibited high selectivity separation for quercetin and its structural analogues using different mobile phases. The material could directly trap a specific class of compounds including quercetin and kaempferol from the hydrolyzate of Ginkgo biloba extract. These results demonstrated the possibility of direct extraction of certain constituents from herb using this material.
Quality assessment of Cortex cinnamomi by HPLC chemical fingerprint, principle component analysis and cluster analysis
Authors: Yang Jie , Chen Li‐Hong , Zhang Qin , Lai Mao‐Xiang , Wang Qiang 
Published: April 2007

AbstractHPLC fingerprint analysis, principle component analysis (PCA), and cluster analysis were introduced for quality assessment of Cortex cinnamomi (CC). The fingerprint of CC was developed and validated by analyzing 30 samples of CC from different species and geographic locations. Seventeen chromatographic peaks were selected as characteristic peaks and their relative peak areas (RPA) were calculated for quantitative expression of the HPLC fingerprints. The correlation coefficients of similarity in chromatograms were higher than 0.95 for the same species while much lower than 0.6 for different species. Besides, two principal components (PCs) have been extracted by PCA. PC1 separated Cinnamomum cassia from other species, capturing 56.75% of variance while PC2 contributed for their further separation, capturing 19.08% variance. The scores of the samples showed that the samples could be clustered reasonably into different groups corresponding to different species and different regions. The scores and loading plots together revealed different chemical properties of each group clearly. The cluster analysis confirmed the results of PCA analysis. Therefore, HPLC fingerprint in combination with chemometric techniques provide a very flexible and reliable method for quality assessment of traditional Chinese medicines.
Determination of seventeen main flavonoids and saponins in the medicinal plant Huang‐qi (Radix Astragali) by HPLC‐DAD‐ELSD
Authors: Yu Qing‐Tao , Qi Lian‐Wen , Li Ping , Yi Ling , Zhao Jing , Bi Zhiming 
Published: April 2007

AbstractA simple, rapid, and reliable method, namely high‐performance liquid chromatography coupled with diode array and evaporative light scattering detectors (HPLC‐DAD‐ELSD), was developed to simultaneously determine twelve major flavonoids and five main saponins in different parts of the medicinal plant Huang‐qi (Radix Astragali). The DAD wavelength was set at 280 nm for the UV detection of flavonoids, while the drift tube temperature was set at 105°C and the nebulizing gas flow rate at 2.7 L/min for ELSD detection of saponins. The method was fully validated with respect to linearity (r2 >0.998), sensitivity, precision, and accuracy (recovery rate between 93.3 and 104.2%). The analytical results of different parts of the medicinal plant Huang‐qi revealed that the levels of total flavonoids or saponins in individual parts can vary considerably and the concentration of each compound in different parts is also significantly different. The aerial parts (stems and leaves) contain even higher total contents of flavonoids (although of different kinds) than the commonly used roots of the plants. In addition, the concentration of total flavonoids and saponins in the extract of the fibrous roots was surprisingly highest among all parts of Astragalus species. All of these findings provide clear evidence and scientific support for utilization of different parts of the medicinal plant Huang‐qi and also for reduction in waste of plant resources.
A comparison of ionic liquids to molecular organic solvents as additives for chiral separations in micellar electrokinetic chromatography
Authors: Mwongela Simon M. , Siminialayi Noreen , Fletcher Kristin A. , Warner Isiah M. 
Published: April 2007

AbstractIn this study, we report the effects of adding ionic liquids (ILs), as compared to adding conventional molecular organic solvents (MOSs), to aqueous buffer solutions containing molecular micelles in the separation of chiral analyte mixtures in micellar EKC (MEKC). The molecular micelle used in this study was polysodium oleyl‐L‐leucylvalinate (poly‐L‐SOLV). The ILs were 1‐alkyl‐3‐methylimidazolium tetrafluoroborate, where the alkyl group was ethyl, butyl, hexyl, or octyl. These ILs were chosen due to their hydrophobicity, good solvating, and electrolyte properties. Thus, it was expected that these ILs would have favorable interactions with chiral analytes and not adversely affect the background current. Common CE buffers, mixed with a molecular micelle, and an IL or a MOS, were used for these chiral separations. The buffers containing an IL in the concentration range of 0.02–0.1 v/v were found to support a reasonable current when an electric field strength of 500 V/cm was applied across the capillary. However, a current break down was observed for the buffers containing more than 60% v/v MOS on application of the above‐mentioned electric field. The chiral resolution and selectivity of the analytes were dependent on the concentration and type of IL or MOS used.
Supported liquid membranes in hollow fiber liquid‐phase microextraction (LPME) – Practical considerations in the three‐phase mode
Authors: Folde Bårdstu Kari , Ho Tung Si , Rasmussen Knut Einar , Pedersen‐Bjergaard Stig , Jönsson Jan Åke 
Published: April 2007

AbstractIn this work, three‐phase liquid‐phase microextraction (LPME) based on a supported liquid membrane (SLM) sustained in the wall of a hollow fiber was investigated with special focus on optimization of the experimental procedures in terms of recovery and repeatability. Recovery data for doxepin, amitriptyline, clomipramine, and mianserin were in the range of 67.8–79.8%. Within‐day repeatability data for the four basic drugs were in the range of 4.1–7.7%. No single factor was found to be responsible for these variations, and the variability was caused by several factors related to the LPME extractions as well as to the final HPLC determination. Although the volume of the SLM varied within 0.4–3.1% RSD depending on the preparation procedure, and the volume of the acceptor solution varied within 4.8% RSD, both recoveries and repeatability were found to be relative insensitive to these variations. Thus, the handling of microliters of liquid in LPME was not a very critical factor, and the preparation of the SLM was accomplished in several different ways with comparable performance. Reuse of hollow fibers was found to suffer from matrix effects due to built‐up of analytes in the SLM, whereas washing of the hollow fibers in acetone was beneficial in terms of recovery, especially for the extraction of the most hydrophobic substances. Several of the organic solvents used in the literature as SLM suffered from poor long‐term stability, but silicone oil AR 20 (polyphenyl‐methylsiloxane), 2‐nitrophenyl octyl ether (NPOE), and dodecyl acetate (DDA) all extracted with unaltered performance even after 60 days of storage at room temperature.
Ultrahigh‐pressure liquid chromatography using a 1‐mm id column packed with 1.5‐μm porous particles
Authors: Anspach Jason A. , Maloney Todd D. , Colón Luis A. 
Published: April 2007

AbstractThe evolution of chromatography has led to the reduction in the size of the packing materials used to fabricate HPLC columns. The increase in the backpressure required has led to this technique being referred to as ultrahigh‐pressure liquid chromatography (UHPLC) when the column backpressure exceeds 10 000 psi (∼︁ 700 bar). Until recently, columns packed with sub‐2‐μm materials have generally fitted into two classes; either short (less than 5 cm) columns designed for use on traditional HPLC systems at pressures less than 5000 psi (350 bar), or capillary columns (inner diameters less than 100 μm). By using packing materials with diameters < 2 μm to fabricate UHPLC columns, there is an increase in efficiency and a decrease in the analysis time that are directly proportional to the size of the packing material. In order to realize and exploit the increase in efficiency, however, the columns must maintain lengths typically associated with analytical columns (15–25 cm). We have packed 1 mm diameter, 150 mm in length columns with 1.5 μm packing material, and evaluated their performance in UHPLC. The pressure required to achieve optimum linear velocities in plots of plate height versus linear velocity was in the vicinity of 1104 bar (16 000 psi). The 1.5 μm particle‐packed column was compared with the more traditional 150 mm long analytical columns packed with 3 μm materials. This column showed an efficiency that was approximately twice that observed with the 3 μm packed column and a concomitant reduction in the analysis time, theoretically predicted.
Pyroelectric coupling in thin film photovoltaics
Authors: Karpov Victor G. , Shvydka Diana 
Published: April 2007

AbstractWe propose a theory of thin film photovoltaics in which one of the polycrystalline films is made of a pyroelectric material grains such as CdS. That film is shown to generate strong polarization improving the device open circuit voltage. Implications and supporting facts for the major photovoltaic types based on CdTe and CuIn(Ga)Se2 absorber layers are discussed.magnified imageBand diagram of a pyroelectric (CdS) based PV junction. Arrows represent the charge carrier photo‐generation.(© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Yellow tea is more potent than other types of tea in suppressing liver toxicity induced by carbon tetrachloride in rats
Authors: Hashimoto Takashi , Goto Miho , Sakakibara Hiroyuki , Oi Naomi , Okamoto Mayumi , Kanazawa Kazuki 
Published: April 2007

AbstractThe present study compared the effects of six Chinese teas categorized by their production process: green, white, yellow, oolong, black and pu‐erh teas, on carbon tetrachloride (CCl4)‐induced liver injury. Wistar rats were given ad libitum the Chinese teas prepared according to the home‐style methods for 1 week, and then intraperitoneally injected with CCl4 (1 mg/kg body weight) or olive oil as a vehicle. The yellow tea significantly ameliorated the increase in the activity of the alanine‐ and aspartate‐aminotransferases in plasma. Thus, the drinking of yellow tea may contribute to protection against liver injury. Copyright © 2007 John Wiley & Sons, Ltd.