bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of flow vortex on a chorded mitral valve in the left ventricle
Authors: Yin M. , Luo X. Y. , Wang T. J. , Watton P. N.
Published: July 2009

An Immersed Boundary fluid–structure interaction model is developed to investigate the dynamic behaviour of a prosthetic chorded mitral valve (MV) inside the left ventricle (LV). In order to simulate more realistic physiological flow conditions, in vivo magnetic resonance images of the LV are used to determine the anatomical structure and the motion of the LV. The LV geometry and its motion are incorporated into the dynamic MV model. This model allows us to investigate the influences of the flow vortex generated by the LV motion on the MV dynamics, as well as the impact of the motion of the chordae attachment points (CAPs). Results are compared with two other cases: (i) an LV model with no prescribed motion of the CAPs, (ii) a Tube model in which the LV is replaced by a tube, although the motion of the chordae is incorporated. These special cases enable the influence of the chordae motion and the vortex on the behaviour of the MV to be analysed independently. It is found that when the MV is placed inside a dynamic LV, the chordae and the valve stretch are significantly increased in the commissural region, and the flow field is strongly asymmetric, with a clockwise single vortex appearing after the early rapid filling phase of the diastole. Given that we impose a flow rate boundary condition, the reverse pressure gradient cannot be established and, hence, the valve does not close properly. Clearly, the presence of the flow vortex alone is not strong enough to aid the valve closure. Copyright © 2009 John Wiley & Sons, Ltd.
A Comparative Study of the Structural, Electronic, and Vibrational Properties of NH3BH3 and LiNH2BH3: Theory and Experiment
Authors: Lee Seung Mi , Kang Xiang‐Dong , Wang Ping , Cheng Hui‐Ming , Lee Young Hee
Published: July 2009

Herein, we systematically investigate the structural, electronic, and vibrational properties of ammonia borane (NH3BH3, AB) and lithium amidoborane (LiNH2BH3, LAB) through both density functional calculations and experiments. AB and LAB samples are generated and their vibrational spectra are obtained by using Fourier transformed infrared spectroscopy (FTIR). The measured vibrational spectra are in good agreement with the calculated ones. Our calculations show that the Li‐related vibration modes are primarily found in the low‐frequency region (<1000 cm−1), and that the intermolecular interactions significantly influence the vibrational spectra. Electronic structure calculations provide insights into the differences between the binding natures of AB and LAB and their influence on the vibrational properties of these compounds.
Carbohydrate‐Derived 1,3‐Diphosphite Ligands as Chiral Nanoparticle Stabilizers: Promising Catalytic Systems for Asymmetric Hydrogenation
Authors: Gual Aitor , Godard Cyril , Philippot Karine , Chaudret Bruno , Denicourt‐Nowicki Audrey , Roucoux Alain , Castillón Sergio , Claver Carmen
Published: July 2009

Metallic Ru, Rh, and Ir nanoparticles were prepared by the decomposition of organometallic precursors under H2 pressure in the presence of 1,3‐diphosphite ligands, derived from carbohydrates, as stabilizing agents. Structural modifications to the diphosphite backbone were found to influence the nanoparticles′ size, dispersion, and catalytic activity. In the hydrogenation of o‐ and m‐methylanisole, the Rh nanoparticles showed higher catalytic activity than the corresponding Ru nanoparticles. The Ir nanoparticles presented the lowest catalytic activity of the series. In all cases, the hydrogenation of o‐methylanisole gave total selectivity for the cis‐product, however, the ee of the product was always less than 6 %. A maximum of 81 % cis‐selectivity was obtained for the hydrogenation of m‐methylanisole, however, no asymmetric induction was observed. These results show that the catalytic activity is affected by a combination of influences from the substrate, the diphosphite ligands, and the metallic nanoparticles.
Identification of adulterants added to beeswax: Estimation of detectable minimum percentages
Authors: Jiménez Juan J. , Bernal José L. , del Nozal Maria J. , Martín Maria T. , Toribio Laura
Published: July 2009

The minimum percentages of adulteration of pure beeswax from Apis mellifera with three paraffins of different melting points and with cow tallow, stearic acid and carnauba wax that can be detected by gas chromatography with flame ionization detection were established. The concentrations of 93 endogenous beeswax compounds such as aliphatic hydrocarbons, olefins, acids, monoesters, alcohols and hydroxyacids were measured in relation to an internal standard (octadecyl octadecanoate) in mixtures of beeswax with the six adulterants; the variation of the concentrations of the compounds with the adulteration percentage was also studied. Percentages higher than 1–4% of each adulterant can be detected in the mixtures. The added adulterant can be identified by the non‐endogenous beeswax compounds observed in the chromatogram; the changes in the concentrations of some beeswax compounds are also useful to corroborate the identification.
Lipid and mineral distribution in different zones of farmed and wild blackspot seabream (Pagellus bogaraveo)
Authors: Álvarez Victoria , Medina Isabel , Prego Ricardo , Aubourg Santiago P.
Published: July 2009

Lipid composition was studied in different white muscle zones (ventral, dorsal and tail) of wild and farmed blackspot seabream (Pagellus bogaraveo). The study was complemented by moisture, trimethylamine oxide (TMAO) and trace mineral determinations. Farmed fish muscle showed higher lipid and triacylglycerol contents, but lower values for moisture, TMAO and α‐tocopherol than its wild fish counterpart; no differences could be observed between both kinds of fish for the phospholipid, sterol and free fatty acid contents. When compared to wild fish, a higher saturated (SFA), monounsaturated (MUFA) and polyunsaturated fatty acid (PUFA) content was obtained in farmed fish, while lower values could be observed for the n‐3/n‐6 and 22:6n‐3/20:5n‐3 fatty acid ratios. Most minerals analysed (Cu, Fe, Mn, Se and Zn) showed higher mean values in farmed fish muscle, except for Ca and Mg which provided higher mean contents in wild fish. Concerning the muscle site comparison, greater SFA, MUFA and PUFA contents could be detected in the dorsal zone than in the two other locations both for farmed and wild fish, in accordance with a higher mean lipid content found at this site. Finally, the tail zone showed higher TMAO values than the two other locations.
Protecting oil during frying: A comparative study
Authors: Aladedunye Felix A. , Przybylski Roman
Published: July 2009

The effect of carbon dioxide blanketing (CDB) and vacuum frying (VF) on the frying performance of regular canola oil was evaluated. For 7 h daily and for 7 days French fries were fried in regular canola oil at 185 ± 5 °C without and with CDB and in a vacuum fryer. The extent of changes in the oil was assessed by analysis of total polar compounds (TPC), anisidine value (AV), color component formation and changes in composition of fatty acids and tocopherols. Frying under CDB reduced the amount of TPC by 54%, while 76% reduction was observed during VF compared to standard frying conditions (SFC). Similarly, lower oxidative degradation was observed when measured by AV. At the end of the frying period, the reduction in unsaturated fatty acid content was 3.8, 1.9 and 12.7% when frying under CDB, vacuum and SFC, respectively. The rate of tocopherol degradation was three and twelve times slower in VF when compared to CDB and SFC, respectively.
Enantioselective Halogenation of β‐Oxo Esters Catalyzed by a Chiral Sulfoximine–Copper Complex
Authors: Frings Marcus , Bolm Carsten
Published: July 2009

A C1‐symmetric amino sulfoximine has been used as a chiral ligand in copper‐catalyzed asymmetric halogenation reactions of β‐oxo esters. Both the catalyst itself and the reaction conditions were optimized, and 26 fluorinated, chlorinated, and brominated products were obtained with enantioselectivities of up to 91 % ee in yields of up to 99 %. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Isotopic Exchange of Hydrogen at C‐5 in Pyrimidine Derivatives: Tautomers with an sp3‐Hybridised C‐5 Carbon Atom
Authors: Dračínský Martin , Holý Antonín , Jansa Petr , Kovačková Soňa , Buděšínský Miloš
Published: July 2009

The proton‐to‐deuterium exchange reaction of the hydrogen atom at the 5‐position of 15 pyrimidine derivatives has been studied. The exchange proceeds under both acidic and alkaline conditions. Under acidic conditions, the mechanism involves protonation at the 5‐position (forming an σ complex), whereas under alkaline conditions the exchange is mainly a result of the formation of a tautomeric equilibrium, with one tautomer bearing an sp3‐hybridised carbon atom at the 5‐position.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Effective elimination of nucleic acids from bacterial protein samples for optimized blue native polyacrylamide gel electrophoresis
Authors: Liang Jingdan , Niu Qiule , Xu Xinping , Luo Yuanming , Zhou Xiufen , Deng Zixin , Wang Zhijun
Published: July 2009

Nucleic acids remaining within bacterial protein samples from Streptomyces lividans and Escherichia coli were found to interfere significantly with blue native polyacrylamide gel electrophoresis (BN‐PAGE), a technique used frequently for analyzing bacterial protein complexes in proteomics studies. We have used ultracentrifugation and/or precipitation of cell lysates with streptomycin sulfate to eliminate nucleic acids from total and/or membrane protein samples. Nucleic acid‐binding proteins were first enriched by precipitation with streptomycin sulfate, and contaminating nucleic acids were then eliminated by precipitation by adding polyethyleneimine. The performance of BN‐PAGE was found to be dramatically improved by these sample preparation steps.
Multi‐user diversity and multiplexing with orthogonal multiple beams in packet‐based wireless systems
Authors: Oh Dong‐Chan , Lee Yong‐Hwan
Published: July 2009

Multiple beams are generated in parallel to achieve multiplexing gain with the use of packet scheduling in wireless systems. However, the use of orthogonal random multiple beams might deteriorate system performance due to inter‐user interference. To alleviate this interference problem, we adjust the number of orthogonal random multiple beams according to the operating condition. To reduce the search complexity for finding optimum orthogonal multi‐beam combination, we further consider the use of a sequential search scheme. Finally, the performance of the proposed schemes is analysed and verified by computer simulation. Numerical results show that the proposed schemes are quite applicable to real environments where the channel information is not perfectly available. Copyright © 2009 John Wiley & Sons, Ltd.
Non‐pecuniary returns to higher education: the effect on smoking intensity in the UK
Authors: Bratti Massimiliano , Miranda Alfonso
Published: July 2009

This paper investigates whether higher education (HE) produces non‐pecuniary returns via a reduction in the intensity of consumption of health‐damaging substances. In particular, it focuses on current smoking intensity of the British individuals sampled in the 29‐year follow‐up survey of the 1970 British Cohort Study. We estimate endogenous dummy ordinal response models for cigarette consumption and show that HE is endogenous with respect to smoking intensity and that even when endogeneity is accounted for, HE is found to have a strong negative effect on smoking intensity. Moreover, pecuniary channels, such as occupation and income, mediate only a minor part of the effect of HE. Our results are robust to modelling individual self‐selection into current smoking participation (at age 29) and to estimating a dynamic model in which past smoking levels affect current smoking levels. Copyright © 2009 John Wiley & Sons, Ltd.
Pan-caspase inhibitor VX-166 reduces fibrosis in an animal model of nonalcoholic steatohepatitis #
Authors: Witek Rafal P. , Stone Carl W. , Karaca Gamze F. , Syn Wing-Kin , Pereira Thiago A. , Agboola Kolade M. , Omenetti Alessia , Jung Youngmi , Teaberry Vanessa , Choi Steve S. , Guy Cynthia D. , Pollard John , Charlton Peter , Diehl Anna Mae
Published: July 2009

Nonalcoholic fatty liver disease (NAFLD) is a potentially progressive liver disease that culminates in cirrhosis. Cirrhosis occurs more often in individuals with nonalcoholic steatohepatitis (NASH) than in those with steatosis (nonalcoholic fatty liver [NAFL]). The difference between NAFL and NASH is the extent of hepatocyte apoptosis, which is more extensive in NASH. Because phagocytosis of apoptotic cells activates hepatic stellate cells (HSCs), we examined the hypothesis that a pan-caspase inhibitor, VX-166, would reduce progression of fibrosis in a mouse model of NASH. Male db/db mice were fed methionine/choline-deficient (MCD) diets to induce NASH and liver fibrosis. Mice were gavaged once daily with either the pan-caspase inhibitor VX-166 (6 mg/kg/d; Vertex, Abingdon, UK) or vehicle only and sacrificed at 4 or 8 weeks. Treatment with an MCD diet increased alanine aminotransferase (ALT), caspase-3 activity, terminal deoxynucleotidyl transferase–mediated dUTP nick-end labeling (TUNEL)-positive cells, NASH, and fibrosis. Treatment of MCD-fed mice with VX-166 decreased active caspase-3, TUNEL-positive cells, and triglyceride content (P < 0.05). However, ALT levels were similar in VX-166–treated mice and vehicle-treated controls. Histological findings also confirmed that both groups had comparable liver injury (NAFLD activity score ≥6). Nevertheless, VX-166–treated MCD-fed mice demonstrated decreased α-smooth muscle actin expression (4 weeks, P < 0.05; 8 weeks, P < 0.005) and had reduced hepatic levels of collagen 1α1 messenger RNA (8 weeks, P < 0.05). Hydroxyproline content and Sirius red staining of VX-166–treated livers confirmed decreases in fibrosis. Conclusion: Inhibiting hepatic apoptosis suppresses the development of fibrosis in mice with NASH. Beneficial effects on liver fibrosis were associated with reductions in hepatic steatosis, but occurred without obvious improvement in liver injury. These findings are consistent with evidence that apoptosis triggers HSC activation and liver fibrosis and suggest that caspase inhibitors may be useful as an antifibrotic NASH therapy. (Hepatology 2009.)
Ectopic growth of hippocampal mossy fibers in a mutated GAP‐43 transgenic mouse with impaired spatial memory retention
Authors: Holahan Matthew R. , Honegger Kyle S. , Routtenberg Aryeh
Published: July 2009

In a previous study, it was shown that transgenic mice, designated G‐NonP, forget the location of a water maze hidden platform when tested 7 days after the last training day (Holahan and Routtenberg (2008) Hippocampus 18:1099–1102). The memory loss in G‐NonP mice might be related to altered hippocampal architecture suggested by the fact that in the rat, 7 days after water maze training, there is discernible mossy fiber (MF) growth (Holahan et al. (2006) Hippocampus 16:560–570; Rekart et al. (2007) Learn Mem 14:416–421). In the present report, we studied the distribution of the MF system within the hippocampus of naïve, untrained, G‐NonP mouse. In WT mice, the MF projection was restricted to the stratum lucidum of CA3 with no detectable MF innervation in distal stratum oriens (dSO). In G‐NonP mice, in contrast, there was an ectopic projection terminating in the CA3 dSO. Unexpectedly, there was nearly a complete loss of immunostaining for the axonal marker Tau1 in the G‐NonP transgenic mice in the MF terminal fields indicating that transgenesis itself leads to off‐target consequences (Routtenberg (1996) Trends Neurosci 19:471–472). Because transgenic mice overexpressing nonmutated, wild type GAP‐43 do not show this ectopic growth (Rekart et al., in press) and the G‐NonP mice overexpress a mutated form of GAP‐43 precluding its phosphorylation by protein kinase C (PKC), the possibility exists that permanently dephosphorylated GAP‐43 disrupts normal axonal fasciculation which gives rise to the ectopic growth into dSO. © 2009 Wiley‐Liss, Inc.
Methoxylated isoflavones, cajanin and isoformononetin, have non‐estrogenic bone forming effect via differential mitogen activated protein kinase (MAPK) signaling
Authors: Bhargavan Biju , Gautam Abnish Kumar , Singh Divya , Kumar Amit , Chaurasia Sumit , Tyagi Abdul Malik , Yadav Dinesh Kumar , Mishra Jay Sharan , Singh Amar Bahadur , Sanyal Sabyasachi , Goel Atul , Maurya Rakesh , Chattopadhyay Naibedya
Published: July 2009

Following a lead obtained from stem‐bark extract of Butea monosperma, two structurally related methoxyisoflavones; cajanin and isoformononetin were studied for their effects in osteoblasts. Cajanin had strong mitogenic as well as differentiation‐promoting effects on osteoblasts that involved subsequent activation of MEK‐Erk and Akt pathways. On the other hand, isoformononetin exhibited potent anti‐apoptotic effect in addition to promoting osteoblast differentiation that involved parallel activation of MEK‐Erk and Akt pathways. Unlike genistein or daidzein, none of these two compounds appear to act via estrogen receptors in osteoblast. Once daily oral (by gavage) treatment for 30 consecutive days was given to recently weaned female Sprague–Dawley rats with each of these compounds at 10.0 mg kg−1 day−1 dose. Cajanin increased bone mineral density (BMD) at all skeletal sites studied, bone biomechanical strength, mineral apposition rate (MAR) and bone formation rate (BFR), compared with control. BMD levels at various anatomic positions were also increased with isoformononetin compared with control however, its effect was less potent than cajanin. Isoformononetin had no effect on the parameters of bone biomechanical strength although it enhanced MAR and BFR compared with control. Isoformononetin had very mild uterotrophic effect, whereas cajanin was devoid of any such effect. Our data suggest that cajanin is more potent than isoformononetin in accelerating peak bone mass achievement. To the best of our knowledge, this work represents the first attempt to elucidate structure‐activity relationship between the two methoxylated isoflavones regarding their effects in osteoblasts and bone formation. J. Cell. Biochem. 108: 388–399, 2009. © 2009 Wiley‐Liss, Inc.
How to obtain statistically converged MM/GBSA results
Authors: Genheden Samuel , Ryde Ulf
Published: July 2009

The molecular mechanics/generalized Born surface area (MM/GBSA) method has been investigated with the aim of achieving a statistical precision of 1 kJ/mol for the results. We studied the binding of seven biotin analogues to avidin, taking advantage of the fact that the protein is a tetramer with four independent binding sites, which should give the same estimated binding affinities. We show that it is not enough to use a single long simulation (10 ns), because the standard error of such a calculation underestimates the difference between the four binding sites. Instead, it is better to run several independent simulations and average the results. With such an approach, we obtain the same results for the four binding sites, and any desired precision can be obtained by running a proper number of simulations. We discuss how the simulations should be performed to optimize the use of computer time. The correlation time between the MM/GBSA energies is ∼5 ps and an equilibration time of 100 ps is needed. For MM/GBSA, we recommend a sampling time of 20–200 ps for each separate simulation, depending on the protein. With 200 ps production time, 5–50 separate simulations are required to reach a statistical precision of 1 kJ/mol (800–8000 energy calculations or 1.5–15 ns total simulation time per ligand) for the seven avidin ligands. This is an order of magnitude more than what is normally used, but such a number of simulations is needed to obtain statistically valid results for the MM/GBSA method. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010
Absorption and fluorescence emission spectroscopic characters of naphtho‐homologated yy‐DNA bases and effect of methanol solution and base pairing
Authors: Zhang Laibin , Li Huifang , Li Jilai , Chen Xiaohua , Bu Yuxiang
Published: July 2009

A comprehensive theoretical study of electronic transitions of naphtho‐homologated base analogs, namely, yy‐T, yy‐C, yy‐A, and yy‐G, was performed. The nature of the low‐lying excited states is discussed, and the results are compared with those from experiment and also with those of y‐bases. Geometrical characteristics of the lowest excited singlet ππ* and nπ* states were explored using the CIS method, and the effects of methanol solution and paring with their complementary natural bases on the relevant absorption and emission spectra of these modified bases were examined. The calculated excitation and emission energies agree well with the measured data, where experimental results are available. In methanol solution, the fluorescence from yy‐A and yy‐G would be expected to occur around 539 and 562 nm, respectively, suggesting that yy‐A is a green‐colored fluorophore, whereas yy‐G is a yellow‐colored fluorophore. The methanol solution was found to red‐shift both the absorption and emission maxima of yy‐A, yy‐T, and yy‐C, but blue‐shift those for yy‐G. Generally, though base pairing has no significant effects on the absorption and fluorescence maxima of yy‐A, yy‐C, and yy‐T, it blue‐shifts those for yy‐G. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010
New one‐step synthesis of pyrazolo[1,5‐a]pyrimidine and pyrazolo[1,5‐a]quinazoline derivatives via multicomponent reactions
Authors: Ghotekar Bhausaheb K. , Jachak Madhukar N. , Toche Raghunath B.
Published: July 2009

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A series of pyrazolopyrimidine and pyrazoloquinozoline derivatives has been synthesized in one step by multicomponent reactions using, 5‐aminopyrazole, p‐substitutedbenzoylacetonitrile/dimedone and triethylorthoesters. pyrazolopyrimidine derivatives were also studied for their absorption and fluorescence maxima. J. Heterocyclic Chem., (2009).
Self termination of ring opening reaction of p‐substituted phenol‐based benzoxazines: An obstructive effect via intramolecular hydrogen bond
Authors: Chirachanchai Suwabun , Laobuthee Apirat , Phongtamrug Suttinun
Published: July 2009

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The ring opening polymerizations of p‐substituted phenol‐based benzoxazines are self‐terminated as soon as dimers form. The polymerization of benzoxazine monomers does not proceed according to the theoretical mechanism even though the conditions, temperature, molar ratio, solvent polarity, and reactant ratio are varied. The speculated mechanism, involving the unique structure of a dimer with inter‐ and intramolecular hydrogen bonds, is applied to explain an obstructive effect on ring opening polymerization. In this article, we clarify an important case which the stereo structure of the compound controls the reaction and prevents the polymerization expected from the theoretical mechanism. J. Heterocyclic Chem., (2009).
Synthesis of 2,4,5‐triaryl‐5H‐chromeno[4,3‐b]pyridines under microwave radiation
Authors: Wu Hui , Wan Yu , Chen Xiu‐Mei , Chen Cai‐Fa , Lu Lei‐Lei , Xin Hai‐Qiang , Xu Hua‐Hong , Pang Li‐Ling , Ma Rui , Yue Cai‐Hui
Published: July 2009

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2,4,5‐Triaryl‐5H‐chromeno[4,3‐b]pyridines were synthesized from a three‐component cascade reaction of 2′‐hydroxyacetophenone, aromatic aldehyde, and ammonium acetate catalyzed by 2‐1′‐methylimidazolium‐3‐yl‐1‐ethyl sulfate under microwave irradiation. Nine new bonds and two new rings were formed in one‐pot. J. Heterocyclic Chem., (2009).
Tissue kallikrein alleviates glutamate‐induced neurotoxicity by activating ERK1
Authors: Liu Ling , Zhang Renliang , Liu Kui , Zhou Houguang , Tang Yuping , Su Jinjin , Yu Xiaoyan , Yang Xuelian , Tang Min , Dong Qiang
Published: July 2009

Glutamate‐induced neurotoxicity consequent to N‐methyl‐D‐aspartic acid (NMDA) and 2‐amino‐3‐(3‐hydroxy‐5‐methyl‐isoxazol‐4‐yl) propionic acid (AMPA) receptor activation underlies the pathogenesis of a wide range of central nervous system disorders, including brain ischemia. Prevention of ischemia/reperfusion (I/R)‐induced neuronal injury has long been regarded as an effective therapeutic strategy for ischemia. Human tissue kallikrein (TK) gene transfer has been shown to protect neurons against cerebral I/R‐induced apoptosis and oxidative stress, via activation of the brandykinin B2 receptor (B2R). However, little is known about the role of TK on glutamate‐induced neurotoxicity. Here we report that pretreatment of cultured cortical neurons with TK largely prevented glutamate‐induced morphological changes and cell death. We found that TK pretreatment alleviated glutamate‐induced oxidative stress by inhibiting neuronal nitric oxide synthase (nNOS) activity, thereby reducing the generation of nitric oxide (NO) and reactive oxygen species (ROS). Blockage of NMDA and AMPA receptors by their specific antagonists MK801 and CNQX had effects similar to those of TK administration. Furthermore, we found that the extracellular signal‐regulated kinase 1/2 cascade (ERK1/2), particularly ERK1, and nuclear factor‐κB (NF‐κB) were involved in TK neuroprotection against glutamate‐induced neurotoxicity. TK pretreatment activated ERK1 and NF‐κB, leading to enhanced expression of brain‐derived neurotrophic factor (BDNF) mRNA and antiapoptotic gene Bcl‐2 protein. Collectively, these findings demonstrate that TK attenuates glutamate‐induced apoptosis through an intracellular signaling pathway including activation of B2R, ERK1/2, and NF‐κB and up‐regulation of BDNF and Bcl‐2 expression. Thus, TK represents a promising therapeutic strategy for ischemic stroke. © 2009 Wiley‐Liss, Inc.
Notch‐Hes1 pathway contributes to the cochlear prosensory formation potentially through the transcriptional down‐regulation of p27Kip1
Authors: Murata Junko , Ohtsuka Toshiyuki , Tokunaga Akinori , Nishiike Suetaka , Inohara Hidenori , Okano Hideyuki , Kageyama Ryoichiro
Published: July 2009

The Notch signaling pathway has a crucial role in the differentiation of hair cells and supporting cells by mediating “lateral inhibition” via the ligands Delta‐like1 (Dll1) and Jagged2 (Jag2) and the effectors Hes1 and Hes5 during mammalian inner ear development. Recently, another Notch ligand, Jagged1 (Jag1)‐dependent Notch activation, has been revealed to be important for the determination of the prosensory region in the earlier stage before cell differentiation. However, little is known about the effectors of the Notch pathway in this context. P27Kip1, a cyclin‐dependent kinase inhibitor, is also known to demarcate the prosensory region in the cochlear primordium, which consists of the sensory progenitors that have completed their terminal mitoses. Hes1 reportedly promotes precursor cell proliferation through the transcriptional down‐regulation of p27Kip1 in the thymus, liver, and brain. In this study, we observed Hes1 as a mediator between the Notch signaling pathway and the regulation of proliferation of sensory precursor cells by p27Kip1 in the developing cochlea. We showed that Hes1, but not Hes5, was weakly expressed at the time of onset of p27Kip1. The expression pattern of Hes1 prior to cell differentiation was similar to that of activated Notch1. P27Kip1 was up‐regulated and BrdU‐positive S‐phase cells were reduced in the developing cochlear epithelium of Hes1 null mice. These results suggest that the Notch‐Hes1 pathway may contribute to the adequate proliferation of sensory precursor cells via the potential transcriptional down‐regulation of p27Kip1 expression and play a pivotal role in the correct prosensory determination. © 2009 Wiley‐Liss, Inc.
O‐linked β‐N‐acetylglucosaminylation in mouse embryonic neural precursor cells
Authors: Yanagisawa Makoto , Yu Robert K.
Published: July 2009

In neural stem cells (NSCs), glycoconjugates and carbohydrate antigens are known not only to serve as excellent cell surface biomarkers for cellular differentiation and development but also to play important functional roles in determining cell fate. O‐linked β‐N‐acetylglucosamine (O‐GlcNAc), which modifies nuclear and cytoplasmic proteins on the serine and threonine residues, is also expected to play an important regulatory role. It is not known, however, whether O‐GlcNAc is expressed in NSCs or what the function of this expression is. In this study, we evaluated the patterns and possible functions of O‐GlcNAcylation in mouse embryonic neuroepithelial cells (NECs), which are known to be rich in NSCs. We confirmed the expression of O‐GlcNAc transferase, O‐GlcNAcase, and several O‐GlcNAcylated proteins in NECs. Treatment of NECs with O‐GlcNAcase inhibitors, PUGNAc and streptozotocin, induced robust accumulation of O‐GlcNAc in NECs and reduction of number of NECs. In O‐GlcNAcase inhibitor‐treated NECs, the Ras‐mitogen‐activated protein kinase pathway and the phosphatidylinositol 3‐kinase‐Akt pathway, important for proliferation and survival, respectively, were intact, but caspase‐3, an executioner for cell death, was activated. These results suggest the possibility that O‐GlcNAc is involved in cell death signaling in NECs. Furthermore, in NECs, we identified an O‐GlcNAc‐modified protein, Sp1 transcription factor. Our study is the first to evaluate expression and functions of O‐GlcNAc in NECs. © 2009 Wiley‐Liss, Inc.
Leukemia inhibitory factor regulates the timing of oligodendrocyte development and myelination in the postnatal optic nerve
Authors: Ishibashi Tomoko , Lee Philip R. , Baba Hiroko , Fields R. Douglas
Published: July 2009

Leukemia inhibitory factor (LIF) promotes the survival of oligodendrocytes both in vitro and in an animal model of multiple sclerosis, but the possible role of LIF signaling in myelination during normal development has not been investigated. We find that LIF−/− mice have a pronounced myelination defect in optic nerve at postnatal day 10. Myelin basic protein (MBP)‐ and proteolipid protein (PLP)‐positive myelin was evident throughout the optic nerve in the wild‐type mice, but staining was present only at the chiasmal region in LIF−/− mice of the same age. Further experiments suggest that the myelination defect was a consequence of a delay in maturation of oligodendrocyte precursor cell (OPC) population. The number of Olig2‐positive cells was dramatically decreased in optic nerve of LIF−/− mice, and the distribution of Olig2‐positive cells was restricted to the chiasmal region of the nerve in a steep gradient toward the retina. Gene expression profiling and cell culture experiments revealed that OPCs from P10 optic nerve of LIF−/− mice remained in a highly proliferative immature stage compared with littermate controls. Interestingly, by postnatal day 14, MBP immunostaining in the LIF−/− optic nerve was comparable to that of LIF+/+ mice. These results suggest that, during normal development of mouse optic nerve, there is a defined developmental time window when LIF is required for correct myelination. Myelination seems to recover by postnatal day 14, so LIF is not necessary for the completion of myelination during postnatal development. © 2009 Wiley‐Liss, Inc.
Bioavailability of dietary sodium copper chlorophyllin and its effect on antioxidant defence parameters of Wistar rats
Authors: Gomes Bárbara B , Barros Sílvia BM , Andrade‐Wartha Elma RS , Silva Ana MO , Silva Vanessa V , Lanfer‐Marquez Ursula M
Published: July 2009

BACKGROUND: There has been growing interest in sodium copper chlorophyllin (Cu‐Chl) as a food colourant and supplement owing to its beneficial biological activities. Studies have revealed that this green pigment inhibits experimental carcinogenesis and interacts with proteins and genotoxic agents. Health‐related activities have also been associated with the prevention of lipid peroxidation. However, intestinal absorption of this pigment has been considered insignificant, raising questions of whether eventual biological properties are related to pre‐ or post‐absorptive actions. In this study, intestinal absorption of Cu‐Chl and its appearance in serum and organs were estimated by high‐performance liquid chromatography analysis in rat feeding experiments. The effect of ingested Cu‐Chl on lipid peroxidation was analysed by measuring thiobarbituric acid‐reactive substances and antioxidant enzyme activities in hepatic and brain tissues of oxidative stress‐induced rats.

RESULTS: The two main components of commercial Cu‐Chl, namely Cu‐chlorin e6 and Cu‐chlorin e4, showed different digestive behaviours, and only Cu‐chlorin e4 was found in serum, liver and kidneys. Antioxidant activity in vivo could be observed in brain and seemed to be related to in situ protection but not to antioxidant enzyme modulation.

CONCLUSION: As at least one of the major components of Cu‐Chl is effectively absorbed, further pharmacokinetic studies are encouraged to access absorption rates and the role of ingested copper chlorophyllins in mammals. Copyright © 2009 Society of Chemical Industry
Biological variation in the colour development of Golden Delicious apples in the orchard
Authors: Tijskens LMM , Unuk Tatjana , Tojnko Stanislav , Hribar Janez , Simčič Marjan
Published: July 2009

BACKGROUND: In managing apple orchards, crop load and rate of nitrogen (N) fertilisation are two factors with a significant influence on fruit quantity and quality, because they affect all physiological processes in the tree. Both factors are strongly related to external and internal fruit quality, especially to skin colour, sugar and acid contents and mineral composition, and consequently to the keeping quality of fruits. The aim of this study was to assess the effects of both factors (three crop load levels and two N fertilisation levels) on the colour development of Golden Delicious apples during the last month on the tree in two consecutive seasons. Data on skin colour (L*, a*, b* values) were analysed using nonlinear mixed effects modelling to extract information on the variation in biological shift factor for colour and to link this variation to the different strategies used concerning N fertilisation and crop load.

RESULTS: The major source of information is contained in the a* value. The behaviour of the a* value could be described by a logistic or an exponential model depending on the season and the experimental set‐up. Nonlinear mixed effects analysis estimating the biological shift factor (maturity) for each individual fruit (random effect) while estimating the rate constant of the decolouration process in common (fixed effect) resulted in explained parts well over 95%.

CONCLUSION: The variation in maturity stage between individual fruits is large. Season has the most profound effect on the estimated values, far more important than that of crop load or fertilisation level. The magnitude of variation in colour due to crop load and N fertilisation is not too large. Its effect on the maturity stage of fruits is more profound: the higher the crop load, the higher the variation. The effect of fertilisation seems to be opposite: the higher the fertilisation level, the lower the variation. Copyright © 2009 Society of Chemical Industry
Technical feasibility and safety of laparoscopy‐assisted total gastrectomy in gastric cancer: A comparative study with laparoscopy‐assisted distal gastrectomy
Authors: Lee Sang Eok , Ryu Keun Won , Nam Byung Ho , Lee Jun Ho , Kim Young‐Woo , Yu Jun Sik , Cho Soo Jeong , Lee Jong Yeul , Kim Chan Gyoo , Choi Il Ju , Kook Myeong Cherl , Park Sook Ryun , Kim Min Ju , Lee Jong Seok
Published: July 2009

Background and Objective

Only a few surgeons with much experience of laparoscopic surgery perform laparoscopy‐assisted total gastrectomy (LATG), because of its technical difficulty and concern about subsequent complications. The aim of this study was to evaluate the technical feasibility and safety of LATG as compared with laparoscopy‐assisted distal gastrectomy (LADG) in gastric cancer.

Methods

From January 2002 to December 2007, LADG was performed in 473 patients and LATG in 67 patients at the Korean National Cancer Center. Surgical procedures and short‐term surgical outcomes of LATG were analyzed.

Results

D2 lymph node dissection was performed in 35 LATG (52.2%) cases and in 274 LADG (57.9%) cases (P = 0.378). Mean blood losses during operation were 156.8 ± 158.0 ml and 190.7 ± 176.2 ml, respectively (P = 0.114). The open conversion rate for LATG was higher than LADG without significance (4.3% vs. 1.7%, P = 0.153). Complications occurred in 18 LATG cases (26.9%) and 38 LADG cases (8.0%) (P < 0.001). The most common postoperative complication of LATG was anastomotic stricture after esophagojejunostomy.

Conclusions

LATG is a technically feasible procedure as compared with LADG. However, its postoperative complication rate is higher than that of LADG, especially that of anastomotic stricture. A more effective anastomotic method during LATG is required to prevent stricture. J. Surg. Oncol. 2009;100:392–395. © 2009 Wiley‐Liss, Inc.
Glycin‐bonded silica monolithic column as zwitterionic stationary phase for hydrophilic interaction pressurized capillary electrochromatography
Authors: Lin Xucong , Zeng Wencan , Wang Xiaochun , Xie Zenghong
Published: July 2009

A novel zwitterionic monolith was prepared by in situ covalent attachment of glycin to a γ‐glycidoxypropyltrimethoxysilane‐modified silica monolith. The monolith possessing in its structure bonded secondary amine groups and carboxylic acid groups was evaluated in pressurized CEC (pCEC) system using small neutral and charged solutes. Owing to the zwitterionic nature of the resulting stationary phase, the direction and magnitude of EOF in this column could be manipulated by adjusting the pH values of the mobile phase. Typical hydrophilic interaction was observed when the ACN content exceeded 45%. Separations of acidic and basic compounds were performed on the prepared column in weakly anodic and cathodic EOF modes, respectively. The organic solvent composition, the salt concentration, and the pH of the mobile phase have effects on the electrochromatographic retention. Besides the hydrophilic interaction and electrophoretic mechanism, electrostatic interactions are also involved in the separations of acids and bases on the zwitterionic column.
Monolithic poly(1,2‐bis(p‐vinylphenyl)ethane) capillary columns for simultaneous separation of low‐ and high‐molecular‐weight compounds
Authors: Greiderer Andreas , Ligon S. Clark , Huck Christian W. , Bonn Günther K.
Published: July 2009

Monolithic poly(1,2‐bis(p‐vinylphenyl)ethane (BVPE)) capillary columns were prepared by thermally initiated free radical polymerisation of 1,2‐bis(p‐vinylphenyl)ethane in the presence of inert diluents (porogens) and α,α′‐azoisobutyronitrile (AIBN) as initiator. Polymerisations were accomplished in 200 μm ID fused silica capillaries at 65°C and for 60 min. Mercury intrusion porosimetry measurements of the polymeric RP support showed a broad bimodal pore‐size‐distribution of mesopores and small macropores in the range of 5–400 nm and flow‐channels in the μm range. N2‐adsorption (BET) analysis resulted in a tremendous enhancement of surface area (101 m2/g) of BVPE stationary phases compared to typical organic monoliths (˜20 m2/g), indicating the presence of a considerable amount of mesopores. Consequently, the adequate proportion of both meso‐ and (small) macropores allowed the rapid and high‐resolution separation of low‐molecular‐weight compounds as well as biomolecules on the same monolithic support. At the same time, the high fraction of flow‐channels provided enhanced column permeability. The chromatographic performance of poly(1,2‐bis(p‐vinylphenyl)ethane) capillary columns for the separation of biomolecules (proteins, oligonucleotides) and small molecules (alkyl benzenes, phenols, phenons) are demonstrated in this article. Additionally, pressure drop versus flow rate measurements of novel poly(1,2‐bis(p‐vinylphenyl)ethane) capillary columns confirmed high mechanical robustness, low swelling in organic solvents and high permeability. Due to the simplicity of monolith fabrication, comprehensive studies of the retention and separation behaviour of monolithic BVPE columns resulted in high run‐to‐run and batch‐to‐batch reproducibilities. All these attributes prove the excellent applicability of monolithic poly(1,2‐bis(p‐vinylphenyl)ethane) capillary columns for μ‐HPLC towards a huge range of analytes of different chemistries and molecular sizes.
Parathyroid surgery and methylene blue: A review with guidelines for safe intraoperative use
Authors: Pollack Geoffrey , Pollack Aron , Delfiner Joel , Fernandez John
Published: July 2009

Methylene blue has been used to help facilitate parathyroid surgery for over 30 years. Its use has been widely considered both safe and cost effective. Twenty‐six cases of a toxic metabolic encephalopathy, however, have been reported with its use. As a result, some surgeons have stopped using this technique altogether. It is now known that methylene blue is a monoamine oxidase inhibitor. When combined with drugs that increase central serotonin neurotransmission, serotonin toxicity results. This is the cause of the encephalopathy described in the literature. A case report, review of the literature, and guidelines as to its proper use are presented so as to allow for safe parathyroid surgery. Laryngoscope, 2009
Attosecond‐precision ultrafast photonics
Authors: Kim J. , Kärtner F.X.
Published: July 2009

We review our recent progress toward attosecond‐precision ultrafast photonics based on ultra‐low timing jitter optical pulse trains from mode‐locked lasers. In femtosecond mode‐locked lasers, the concentration of a large number of photons in an extremely short pulse duration enables the scaling of timing jitter into the attosecond regime. To characterize such jitter levels, we developed new attosecond‐resolution measurement techniques and show that standard fiber lasers can achieve sub‐fs high‐frequency jitter. By leveraging the ultra‐low jitter of free‐running mode‐locked lasers, we pursued high‐precision optical‐optical and optical‐microwave synchronization techniques. Optical signals spanning 1.5 octaves were synthesized by attosecond‐precision timing and phase synchronization of two independent mode‐locked lasers. High‐stability microwave signals were also synthesized from mode‐locked lasers with drift‐free sub‐10‐fs precision. We further demonstrated the attosecond‐precision distribution of optical pulse trains to remote locations via timing‐stabilized fiber links. Finally, the application of optical pulse trains for high‐resolution sampling and analog‐to‐digital conversion is discussed.
Continuous‐variable quantum information processing
Authors: Andersen U.L. , Leuchs G. , Silberhorn C.
Published: July 2009

Observables of quantum systems can possess either a discrete or a continuous spectrum. For example, upon measurements of the photon number of a light state, discrete outcomes will result whereas measurements of the light's quadrature amplitudes result in continuous outcomes. If one uses the continuous degree of freedom of a quantum system for encoding, processing or detecting information, one enters the field of continuous‐variable (CV) quantum information processing. In this paper we review the basic principles of CV quantum information processing with main focus on recent developments in the field. We will be addressing the three main stages of a quantum information system; the preparation stage where quantum information is encoded into CVs of coherent states and single‐photon states, the processing stage where CV information is manipulated to carry out a specified protocol and a detection stage where CV information is measured using homodyne detection or photon counting.
Acetylation of Cellulose Nanowhiskers with Vinyl Acetate under Moderate Conditions
Authors: Çetin Nihat Sami , Tingaut Philippe , Özmen Nilgül , Henry Nathan , Harper David , Dadmun Mark , Sèbe Gilles
Published: July 2009

A novel and straightforward method for the surface acetylation of cellulose nanowhiskers by transesterification of vinyl acetate is proposed. The reaction of vinyl acetate with the hydroxyl groups of cellulose nanowhiskers obtained from cotton linters was examined with potassium carbonate as catalyst. Results indicate that during the first stage of the reaction, only the surface of the nanowhiskers was modified, while their dimensions and crystallinity remained unchanged. With increasing reaction time, diffusion mechanisms controlled the rate, leading to nanowhiskers with higher levels of acetylation, smaller dimensions, and lower crystallinity. In THF, a solvent of low polarity, the suspensions from modified nanowhiskers showed improved stability with increased acetylation.

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New, Hydrophilic, HPMA‐Based Polymers for Bioresponsive Shielding of Gene‐Delivery Vectors
Authors: Laga Richard , Koňák Čestmír , Šubr Vladimír , Ulbrich Karel
Published: July 2009

New, hydrophilic polymers and copolymers based on HPMA, carrying reactive thiazolidine‐2‐thione groups either situated at the polymer chain end or randomly distributed along the chains bound to the polymer backbone via spacers containing reductively degradable disulfide linkages, have been developed for an efficient and intracellularly removable coating of gene‐delivery vectors. Amino‐group‐bearing PS‐latex nanoparticles and self‐assembled poly(L‐lysine)/DNA complexes were used as models for gene‐delivery viral and nonviral vectors to study the coating reaction with reactive HPMA‐based (co)polymers. It is shown that modification of the particles was effective, resulting in an increase in the $\overline M _{\rm w} $ and Rh of the particles, which depend on the polymer length and its detailed structure. Incubation of the coated particles in buffers modeling the intracellular environment induced unshielding of the vectors and release of the polymer layer from their surface.

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Luminescent Multi‐Layered Polymer Coating for the Simultaneous Detection of Oxygen Pressure and Temperature
Authors: Hyakutake Tsuyoshi , Taguchi Hiroyuki , Kato Junji , Nishide Hiroyuki , Watanabe Masahiro
Published: July 2009

A triple‐layered luminescent polymer coating was prepared to simultaneously detect both oxygen and temperature upon the coating. The coating was composed of an oxygen and a temperature sensory layer based on platinumporphyrin (PtTFP) and ruthenium phenanthroline (Ru(phen)) dye molecule, respectively. The temperature‐sensitive Ru(phen) was dispersed in gas‐barrier polyvinyl alcohol as the first layer, which was further coated with a water‐proofing fluorine‐containing polymer. The oxygen sensory layer composed of the oxygen‐sensitive PtTFP and high oxygen‐permeative poly(1‐trimethylsilyl‐1‐propyne) was coated as the third layer. The two luminescences were separately monitored: the oxygen partial pressure and temperature in the range of 0–21 kPa and of 25–120 °C were successfully detected.

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Expanded Core/Shell Poly(vinyl acetate)/Poly(vinyl alcohol) Particles for Embolization
Authors: Peixoto Luciana S. , Melo Príamo A. , Nele Márcio , Pinto José Carlos
Published: July 2009

An improvement to a previously published suspension polymerization process for the production of spherical core/shell PVAc/PVA particles is described. To increase the settling time of the beads in the suspension, an expansion stage was introduced. The core/shell structure was obtained through the partial hydrolysis of the PVAc. The particle density was manipulated through addition of a solvent during the suspension polymerization stage and posterior expansion of the polymer beads obtained at the end of the process. This technique allows for effective reduction of the density of the final polymer beads. The expansion stage exerts also a beneficial effect on particle drying, avoiding particle aggregation during post‐polymerization processing of the polymer beads.

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