bluuebunny/crossref_metadata_2025_split huggingface dataset:
Separation of viable and nonviable animal cell using dielectrophoretic filter
Authors: Hakoda Masaru , Wakizaka Yoshikazu , Hirota Yusuke 
Published: February 2010

AbstractSelective separation of cells using dielectrophoresis (DEP) has recently been studied and methods have been proposed. However, these methods are not applicable to large‐scale separation because they cannot be performed efficiently. In DEP separation, the DEP force is effective only when it is applied close to the electrodes. Utilizing a DEP filter is a solution for large‐scale separation. In this article, the separation efficiency for viable and nonviable cells in a DEP filter was examined. The effects of an applied AC electric field frequency and the gradient of the squared electric field intensity on a DEP velocity for the viable and nonviable animal cells (3‐2H3 cell) were discussed. The frequency response of the DEP velocity differed between the viable and the nonviable cells. We deducted an empirical equation that can be used as guiding principle for the DEP separation. The results indicate that the viable and the nonviable cells were separated using the DEP filter, and the best operating conditions such as the applied voltage and the flow rate were discussed. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Fluid flow through a high cell density fluidized‐bed during centrifugal bioreactor culture
Authors: Detzel Christopher J. , Van Wie Bernard J. , Ivory Cornelius F. 
Published: February 2010

AbstractAn increasing demand for products such as tissues, proteins, and antibodies from mammalian cell suspension cultures is driving interest in increasing production through high‐cell density bioreactors. The centrifugal bioreactor (CCBR) retains cells by balancing settling forces with surface drag forces due to medium throughput and is capable of maintaining cell densities above 108 cells/mL. This article builds on a previous study where the fluid mechanics of an empty CCBR were investigated showing fluid flow is nonuniform and dominated by Coriolis forces, raising concerns about nutrient and cell distribution. In this article, we demonstrate that the previously reported Coriolis forces are still present in the CCBR, but masked by the presence of cells. Experimental dye injection observations during culture of 15 μm hybridoma cells show a continual uniform darkening of the cell bed, indicating the region of the reactor containing cells is well mixed. Simulation results also indicate the cell bed is well mixed during culture of mammalian cells ranging in size from 10 to 20 μm. However, simulations also allow for a slight concentration gradient to be identified and attributed to Coriolis forces. Experimental results show cell density increases from 0.16 to 0.26 when centrifugal force is doubled by increasing RPM from 650 to 920 at a constant inlet velocity of 6.5 cm/s; an effect also observed in the simulation. Results presented in this article indicate cells maintained in the CCBR behave as a high‐density fluidized bed of cells providing a homogeneous environment to ensure optimal growth conditions. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Antifibrillizing agents catalyze the formation of unstable intermediate aggregates of beta‐amyloid
Authors: Wang Min S. , Boddapati Shanta , Sierks Michael R. 
Published: February 2010

AbstractAlthough Alzheimer's disease (AD) is characterized by the extracellular deposition of fibrillar aggregates of beta‐amyloid (Aβ), transient oligomeric species of Aβ are increasingly implicated in the pathogenesis of AD. Natively unfolded monomeric Aβ can misfold and progressively assemble into fibrillar aggregates, following a well‐established “on pathway” seeded‐nucleation mechanism. Here, we show that three simple saccharides, mannose, sucrose, and raffinose, alter Aβ aggregation kinetics and morphology. The saccharides inhibit formation of Aβ fibrils but promote formation of various oligomeric aggregate species through different “off pathway” aggregation mechanisms at 37°C but not at 60°C. The various oligomeric Aβ aggregates formed when coincubated with the different saccharides are morphologically distinct but all are toxic toward SH‐SY5Y human neuroblastoma cells, increasing the level of toxicity and greatly prolonging toxicity compared with Aβ alone. As a wide variety of anti‐Aβ aggregation strategies are being actively pursued as potential therapeutics for AD, these studies suggest that care must be taken to ensure that the therapeutic agents also block toxic oligomeric Aβ assembly as well as inhibit fibril formation. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
The improvement of chloroperoxidase activities in the presence of ammonium salts and cationic surfactants
Authors: Ru Xuejiao , Wu Jinyue , Guo Huan , Jiang Yucheng , Hu Mancheng , Zhai Quanguo , Li Shuni 
Published: February 2010

AbstractThe catalytic activities of chloroperoxidase (CPO) including halogenation, oxidation, and peroxidation were investigated in the presence of ammonium salts: tetramethylammonium bromide (TMABr), tetraethylammonium bromide (TEABr), tetrapropylammonium bromide (TPABr), tetrabutylammonium bromide (TBABr), and cationic surfactants: dodecyltrimethylammonium bromide (DTABr) and cetyltrimethylammonium bromide (CTABr). All the mentioned activities were promoted in most cases. The highest modified activity (ABTS peroxidation) was 18.16 times higher in the presence of TMABr than that in pure buffer. The activity enhancement was strongly dependent on the concentration and the hydrophobic chain length of additives, and the structure of substrates. The kinetic parameters showed that the activation was mainly attributed to an increase in kcat due probably to a catalytically favorable conformation of CPO induced by the additives. Moreover, a lower Km and higher ratio of kcat/Km (specificity constant) was obtained, indicating that both the affinity and specificity of CPO to substrates were improved in the presence of additives. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Transcriptomic responses to sodium chloride‐induced osmotic stress: A study of industrial fed‐batch CHO cell cultures
Authors: Shen Duan , Kiehl Thomas R. , Khattak Sarwat F. , Li Zheng Jian , He Aiqing , Kayne Paul S. , Patel Vishal , Neuhaus Isaac M. , Sharfstein Susan T. 
Published: February 2010

AbstractThe rapidly expanding market for monoclonal antibody and Fc‐fusion‐protein therapeutics has increased interest in improving the productivity of mammalian cell lines, both to alleviate capacity limitations and control the cost of goods. In this study, we evaluated the responses of an industrial CHO cell line producing an Fc‐fusion‐protein to hyperosmotic stress, a well‐known productivity enhancer, and compared them with our previous studies of murine hybridomas (Shen and Sharfstein, Biotechnol Bioeng. 2006;93:132–145). In batch culture studies, cells showed substantially increased specific productivity in response to increased osmolarity as well as significant metabolic changes. However, the final titer showed no substantial increase due to the decrease in viable cell density. In fed batch cultures, hyperosmolarity slightly repressed the cellular growth rate, but no significant change in productivity or final titer was detected. To understand the transcriptional responses to increased osmolarity and relate changes in gene expression to increased productivity and repressed growth, proprietary CHO microarrays were used to monitor the transcription profile changes in response to osmotic stress. A set of osmotically regulated genes was generated and classified by extracting their annotations and functionalities from online databases. The gene list was compared with results previously obtained from similar studies of murine‐hybridoma cells. The overall transcriptomic responses of the two cell lines were rather different, although many functional groups were commonly perturbed between them. Building on this study, we anticipate that further analysis will establish connections between productivity and the expression of specific gene(s), thus allowing rational engineering of mammalian cells for higher recombinant‐protein productivity. © 2010 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Microarray data classification using inductive logic programming and gene ontology background information
Authors: Ryeng Einar , Alsberg Bjørn Kåre 
Published: February 2010

AbstractThere exists many databases containing information on genes that are useful for background information in machine learning analysis of microarray data. The gene ontology and gene ontology annotation projects are among the most comprehensive of these. We demonstrate how inductive logic programming (ILP) can be used to build classification rules for microarray data which naturally incorporates the gene ontology and annotations to it as background knowledge without removing the inherent graph structure of the ontology. The ILP rules generated are parsimonious and easy to interpret. Copyright © 2010 John Wiley & Sons, Ltd.
Efficient Intramolecular Hydroalkoxylation of Unactivated Alkenols Mediated by Recyclable Lanthanide Triflate Ionic Liquids: Scope and Mechanism
Authors: Dzudza Alma , Marks Tobin J. 
Published: February 2010

AbstractLanthanide triflate complexes of the type [Ln(OTf)3] (Ln=La, Sm, Nd, Yb, Lu) serve as effective, recyclable catalysts for the rapid intramolecular hydroalkoxylation (HO)/cyclization of primary/secondary and aliphatic/aromatic hydroxyalkenes in imidazolium‐based room‐temperature ionic liquids (RTILs) to yield the corresponding furan, pyran, spirobicyclic furan, spirobicyclic furan/pyran, benzofuran, and isochroman derivatives. Products are straightforwardly isolated from the catalytic solution, conversions exhibit Markovnikov regioselectivity, and turnover frequencies are as high as 47 h−1 at 120 °C. The ring‐size rate dependence of the primary alkenol cyclizations is 5>6, consistent with a sterically controlled transition state. The hydroalkoxylation/cyclization rates of terminal alkenols are slightly more rapid than those of internal alkenols, which suggests modest steric demands in the cyclic transition state. Cyclization rates of aryl‐functionalized hydroxyalkenes are more rapid than those of the linear alkenols, whereas five‐ and five/six‐membered spirobicyclic skeletons are also regioselectively closed. In cyclization of primary, sterically encumbered alkenols, turnover‐frequency dependence on metal‐ionic radius decreases by approximately 80‐fold on going from La3+ (1.160 Å) to Lu3+ (0.977 Å), presumably reflecting steric impediments along the reaction coordinate. The overall rate law for alkenol hydroalkoxylation/cyclization is v≈k[catalyst]1[alkenol]1. An observed ROH/ROD kinetic isotope effect of 2.48 (9) is suggestive of a catalytic pathway that involves kinetically significant intramolecular proton transfer. The present activation parameters—enthalpy (ΔH≠)=18.2 (9) kcal mol−1, entropy (ΔS≠)=−17.0 (1.4) eu, and energy (Ea)=18.2 (8) kcal mol−1—suggest a highly organized transition state. Proton scavenging and coordinative probing results suggest that the lanthanide triflates are not simply precursors of free triflic acid. Based on the kinetic and mechanistic evidence, the proposed catalytic pathway invokes hydroxyl and olefin activation by the electron‐deficient Ln3+ center, and intramolecular H+ transfer, followed by alkoxide nucleophilic attack with ring closure.
Mechanistic Exploration of Intramolecular Aminodiene Hydroamination/Cyclisation Mediated by Constrained Geometry Organoactinide Complexes: A DFT Study
Authors: Tobisch Sven 
Published: February 2010

AbstractThe present computational mechanistic study explores comprehensively the organoactinide‐mediated intramolecular hydroamination/cyclisation (IHC) of aminodienes by employing a reliable DFT method. All the steps of a plausible catalytic reaction course have been scrutinised for the IHC of (4E,6)‐heptadienylamine 1 t by [(CGC)Th(NMe2)2] precatalyst 2 (CGC=[Me2Si(η5‐Me4C5)(tBuN)]2−). For each of the relevant elementary steps the most accessible pathway has been identified from a multitude of mechanistic possibilities. The operative mechanism involves rapid substrate association/dissociation equilibria for the 3 t‐S resting state and also for azacyclic intermediates 4 a, 4 s, easily accessible and reversible exocyclic ring closure, supposedly facile isomerisation of the azacycle’s butenyl tether prior to turnover‐limiting protonolysis. The following aspects are in support of this scenario: 1) the derived rate law is consistent with the experimentally obtained empirical rate law; 2) the accessed barrier for turnover‐limiting protonolysis does agree remarkably well with observed performance data; 3) the ring‐tether double‐bond selectivity is consistently elucidated, which led to predict the product distribution correctly. This study provides a computationally substantiated rationale for observed activity and selectivity data. Steric demands at the CGC framework appear to be an efficient means for modulating both performance and ring‐tether double‐bond selectivity. The careful comparison of (CGC)4f‐element and (CGC)5f‐element catalysts revealed that aminodiene IHC mediated by organoactinides and organolanthanides proceeds through a similar mechanistic scenario. However, cyclisation and protonolysis steps, in particular, feature a markedly different reactivity pattern for the two catalyst classes, owing to enhanced bond covalency of early actinides when compared to lanthanides.
Functionalization of Organic Molecules by Transition‐Metal‐Catalyzed C(sp3)H Activation
Authors: Jazzar Rodolphe , Hitce Julien , Renaudat Alice , Sofack‐Kreutzer Julien , Baudoin Olivier 
Published: February 2010

AbstractTransition‐metal‐catalyzed CH activation has recently emerged as a powerful tool for the functionalization of organic molecules. While many efforts have focused on the functionalization of arenes and heteroarenes by this strategy in the past two decades, much less research has been devoted to the activation of non‐acidic CH bonds of alkyl groups. This Minireview highlights recent work in this area, with a particular emphasis on synthetically useful methods.
Chelation versus Binucleation: Metal Complex Formation with the Hexadentate all‐cis‐N1,N2‐Bis(2,4,6‐trihydroxy‐3,5‐diaminocyclohexyl)ethane‐1,2‐diamine
Authors: Bartholomä Mark , Gisbrecht Sergej , Stucky Stefan , Neis Christian , Morgenstern Bernd , Hegetschweiler Kaspar 
Published: February 2010

AbstractThe hexadentate ligand all‐cis‐N1,N2‐bis(2,4,6‐trihydroxy‐3,5‐diaminocyclohexyl)ethane‐1,2‐diamine (Le) was synthesized in five steps with an overall yield of 39 % by using [Ni(taci)2]SO4⋅4 H2O as starting material (taci=1,3,5‐triamino‐1,3,5‐trideoxy‐cis‐inositol). Crystal structures of [Na0.5(H6Le)](BiCl6)2Cl0.5⋅4 H2O (1), [Ni(Le)]‐ Cl2⋅5 H2O (2), [Cu(Le)](ClO4)2⋅H2O (3), [Zn(Le)]CO3⋅7 H2O (4), [Co(Le)](ClO4)3 (5 c), and [Ga(H−2Le)]‐ NO3⋅2 H2O (6) are reported. The Na complex 1 exhibited a chain structure with the Na+ cations bonded to three hydroxy groups of one taci subunit of the fully protonated H6(Le)6+ ligand. In 2, 3, 4, and 5 c, a mononuclear hexaamine coordination was found. In the Ga complex 6, a mononuclear hexadentate coordination was also observed, but the metal binding occurred through four amino groups and two alkoxo groups of the doubly deprotonated H−2(Le)2−. The steric strain within the molecular framework of various M(Le) isomers was analyzed by means of molecular mechanics calculations. The formation of complexes of Le with MnII, CuII, ZnII, and CdII was investigated in aqueous solution by using potentiometric and spectrophotometric titration experiments. Extended equilibrium systems comprising a large number of species were observed, such as [M(Le)]2+, protonated complexes [MHz(Le)]2+z and oligonuclear aggregates. The pKa values of H6(Le)6+ (25 °C, μ=0.10 m) were found to be 2.99, 5.63, 6.72, 7.38, 8.37, and 9.07, and the determined formation constants (log β) of [M(Le)]2+ were 6.13(3) (MnII), 20.11(2) (CuII), 13.60(2) (ZnII), and 10.43(2) (CdII). The redox potentials (vs. NHE) of the [M(Le)]3+/2+ couples were elucidated for Co (−0.38 V) and Ni (+0.90 V) by cyclic voltammetry.
Spermine‐Functionalized Perylene Bisimide Dyes—Highly Fluorescent Bola‐Amphiphiles in Water
Authors: Rehm Stefanie , Stepanenko Vladimir , Zhang Xin , Rehm Thomas H. , Würthner Frank 
Published: February 2010

AbstractA series of four spermine‐functionalized perylene bisimide dyes without linkers (1) and with linkers (2–4) between the chromophore and the polyamine was synthesized. Protonation of the spermine moieties resulted in the formation of highly water‐soluble dyes with up to six positively charged ammonium ions. The aggregation behavior of these strongly fluorescent bola‐amphiphiles was studied in pure water as solvent by UV/Vis and fluorescence spectroscopy, and an astonishingly high fluorescence quantum yield of up to Φfl=0.90 was observed for PBI 1. Atomic force microscopy and transmission electron microscopy were applied for the visualization of the aggregates on surfaces. Molecular modeling studies were performed by force‐field calculations to explore the aggregate morphologies, which also provided valuable information on the influence of the additional alkylcarbonyl linkers. Our detailed spectroscopic and microscopic investigations revealed that the excellent optical properties of perylene bisimide chromophores can be used even in pure deionized water if their aggregation is efficiently suppressed.
Determination of catechin diastereomers from the leaves of Byrsonima species using chiral HPLC‐PAD‐CD
Authors: Rinaldo Daniel , Batista João M. , Rodrigues Juliana , Benfatti Ana C. , Rodrigues Clenilson M. , Dos Santos Lourdes C. , Furlan Maysa , Vilegas Wagner 
Published: February 2010

AbstractWhen catechins are found in plant extracts, they are almost always identified as catechin and/or epicatechin probably due to stereoselectivity of the enzymes involved in the biosynthesis of these substances. However, the lack of reports regarding to ent‐catechin as well as ent‐epicatechin does not necessarily mean that these compounds have not been produced. In fact, most of the previous reports used chromatographic conditions not suitable for such separation. This article describes a simple and reliable analytical HPLC‐PAD‐CD method for simultaneous determination of catechin diastereomers both in infusions and extracts from the leaves of Byrsonima species. The direct separation of catechin, ent‐catechin, epicatechin, and ent‐epicatechin was obtained in normal phase by HPLC‐PAD‐CD using Chiralcel OD‐H as chiral stationary phase and n‐hexane/ethanol with 0.1% of TFA as mobile phase. Chirality, 2010. © 2010 Wiley‐Liss, Inc.
MR molecular imaging of HER‐2 in a murine tumor xenograft by SPIO labeling of anti‐HER‐2 affibody
Authors: Kinoshita Manabu , Yoshioka Yoshichika , Okita Yoshiko , Hashimoto Naoya , Yoshimine Toshiki 
Published: February 2010

AbstractIn vivo molecular imaging is a rapidly growing research area both for basic and clinical science. Non‐invasive imaging of in vivo conditions at the molecular level increases understanding of the biological characteristics of normal and diseased tissues without the need for invasive surgical procedures. Among the various imaging modalities, magnetic resonance imaging (MRI) has garnered interest as a molecular imaging modality due to its high spatial resolution. Here, we have demonstrated that the combined use of HER‐2 targeting affibody, a small 7 kDa molecule that behaves similarly to antibodies, and superparamagnetic iron oxide (SPIO) can non‐invasively image HER‐2 expressing cells or tissues both in vitro and in vivo by MRI. This preliminary study demonstrates that affibody‐SPIO is a feasible, target‐specific contrast agent for in vivo MR molecular imaging. Copyright © 2010 John Wiley & Sons, Ltd.
Evaluation of rHA labeled with Gd–DTPA for blood pool imaging and targeted contrast delivery
Authors: Wild Jim M. , Woodrow John , van Beek Edwin J.R. , Misselwitz Bernd , Johnson Richard 
Published: February 2010

AbstractA new contrast agent was developed by linking Gd–DTPA chelate to recombinant human albumin in the laboratory. The molar relaxivity of the new agent was tested in aqueous solution at B0 1.5 T and temperature 20°C. The soluble compound had a higher molar longitudinal relaxivity and molar transverse relaxivity in water (r1 = 7.2 s−1 mM−1, r2 = 18.4 s−1 mM−1) than those measured for Gd–DTPA solution (r1 = 3.5 s−1 mM−1, r2 = 5.5 s−1 mM−1). The performance of the compound as a blood pool agent was investigated with soluble and microparticulate forms of the compound and comparisons were made with Gd–DTPA and the polymeric blood‐pool agent, Gadomer. T1‐weighted imaging experiments show that the soluble compound acts as a highly effective blood pool agent with hyperintensity in the vasculature persisting beyond 2 h post administration, compared with free Gd–DTPA, which was cleared from the blood pool after approximately 10 min. The clearance kinetics of the new agents were examined, due to the incomplete elimination within 14 days post injection; both rHA labeled compounds are probably not suitable for development as routine blood pool contrast media. However, with free sites on the Gd‐loaded rHA molecule, there are possibilities for binding the agent to antibodies in the laboratory, which was demonstrated, and thus there exist potential applications for in vivo molecular imaging with this agent. Copyright © 2010 John Wiley & Sons, Ltd.
The role of socioeconomic status in adjustment after ductal carcinoma in situ
Authors: de Moor Janet S. , Partridge Ann H. , Winer Eric P. , Ligibel Jennifer , Emmons Karen M. 
Published: February 2010

AbstractBACKGROUND:A large body of literature suggests that socioeconomic status (SES) is positively associated with mental and physical health. However, little research has examined the impact of SES on psychological adjustment after a major stressor. The current study examined whether SES (education and financial status) was associated with distress (anxiety and depression) in women diagnosed with ductal carcinoma in situ (DCIS). This study also explored whether social support explained the association between SES and distress and whether social support buffered the impact of low SES on distress.METHODS:A total of 487 women with newly diagnosed DCIS were enrolled in the study. Participants completed questions about sociodemographic, psychosocial, and clinical characteristics at the time of enrollment and 9 months after their diagnosis.RESULTS:Financial status was inversely associated with anxiety and depression at the 9‐month follow‐up. Financial status also predicted change in anxiety and depression. Women with high financial status reported a decline in anxiety and depression during the study period, whereas women with medium or low financial status reported an increase in anxiety and depression. In addition, the probability of exceeding the screening threshold suggestive of clinical depression increased with decreasing financial status. Education was not associated with anxiety or depression. The presence of social support did not explain the association between financial status and change in distress. Social support did not buffer the effect of low SES on anxiety and depression.CONCLUSIONS:Women with medium or low SES were vulnerable to escalating anxiety and depression after a DCIS diagnosis. Cancer 2010. © 2010 American Cancer Society.