bluuebunny/crossref_metadata_2025_split huggingface dataset:
Combined effects of solvation and aggregation propensity on the final supramolecular structures adopted by hydrophobic, glycine‐rich, elastin‐like polypeptides
Authors: Salvi Anna M. , Moscarelli Pasquale , Bochicchio Brigida , Lanza Giuseppe , Castle James E. 
Published: September 2012

AbstractPrevious work on elastin‐like polypeptides (ELPs) made of hydrophobic amino acids of the type XxxGlyGlyZzzGly (Xxx, Zzz = Val, Leu) has consistently shown that differing dominant supramolecular structures were formed when the suspending media were varied: helical, amyloid‐like fibers when suspended in water and globules evolving into “string of bead” structures, poly(ValGlyGlyValGly), or cigar‐like bundles, poly(ValGlyGlyLeuGly), when suspended in methyl alcohol. Comparative experiments with poly(LeuGlyGlyValGly) have further indicated that the interface energy plays a significant role and that solvation effects act in concomitance with the intrinsic aggregation propensity of the repeat sequence. Continuing our investigation on ELPs using surface (X‐ray photoelectron spectroscopy, atomic force microscopy) and bulk (circular dichroism, Fourier transform infrared spectroscopy) techniques for their characterization, here we have compared the effect of suspending solvents (H2O, dimethylsulfoxide, ethylene glycol, and MeOH) on poly(ValGlyGlyValGly), the polypeptide most inclined to form long and well‐refined helical fibers in water, searching for the signature of intermolecular interactions occurring between the polypeptide chains in the given suspension. The influence of sequence specificities has been studied by comparing poly(ValGlyGlyValGly) and poly(LeuGlyGlyValGly) with a similar degree of polymerization. Deposits on substrates of the polypeptides were characterized taking into account the differing evaporation rate of solvents, and tests on their stability in ultra high vacuum were performed. Finally, combining experimental and computational studies, we have revaluated the three‐dimensional modeling previously proposed for the supramolecular assembly in water of poly(ValGlyGlyValGly). The results were discussed and rationalized also in the light of published data. © 2012 Wiley Periodicals, Inc. Biopolymers 99: 292–292, 2013.
Cytochrome P450‐catalyzed O‐dealkylation coupled with photochemical NADPH regeneration
Authors: Lee Sahng Ha , Kwon Yong‐Chan , Kim Dong‐Myung , Park Chan Beum 
Published: September 2012

AbstractCytochrome P450 monooxygenases are multifunctional enzymes with potential applications in chemoenzymatic synthesis of complex chemicals as well as in studies of metabolism and xenobiotics. Widespread application of cytochrome P450s, however, is encumbered by the critical need for redox equivalents in their catalytic function. To overcome this limitation, we studied visible light‐driven regeneration of NADPH for P450‐catalyzed O‐dealkylation reaction; we used eosin Y as a photosensitizing dye, triethanolamine as an electron donor, and [Cp*Rh(bpy)H2O] as an electron mediator. We analyzed catalytic activity of cell‐free synthesized P450 BM3 monooxygenase variant (Y51F/F87A, BM3m2) in the presence of key components for NADPH photoregeneration. The P450‐catalyzed O‐dealkylation reaction sustainably maintained its turnover with the continuous supply of photoregenerated NADPH. Visible light‐driven, non‐enzymatic NADPH regeneration provides a new route for efficient, sustainable utilization of P450 monooxygenases. Biotechnol. Bioeng. 2013; 110: 383–390. © 2012 Wiley Periodicals, Inc.
Overexpression of O‐methyltransferase leads to improved vanillin production in baker's yeast only when complemented with model‐guided network engineering
Authors: Brochado Ana Rita , Patil Kiran R. 
Published: September 2012

AbstractOverproduction of a desired metabolite is often achieved via manipulation of the pathway directly leading to the product or through engineering of distant nodes within the metabolic network. Empirical examples illustrating the combined effect of these local and global strategies have been so far limited in eukaryotic systems. In this study, we compared the effects of overexpressing a key gene in de novo vanillin biosynthesis (coding for O‐methyltransferase, hsOMT) in two yeast strains, with and without model‐guided global network modifications. Overexpression of hsOMT resulted in increased vanillin production only in the strain with model‐guided modifications, exemplifying advantage of using a global strategy prior to local pathway manipulation. Biotechnol. Bioeng. 2013; 110: 656–659. © 2012 Wiley Periodicals, Inc.
Enhancement of extracellular electron transfer and bioelectricity output by synthetic porin
Authors: Yong Yang‐Chun , Yu Yang‐Yang , Yang Yun , Liu Jing , Wang Jing‐Yuan , Song Hao 
Published: September 2012

AbstractThe microbial fuel cell (MFC), is a promising environmental biotechnology for harvesting electricity energy from organic wastes. However, low bacterial membrane permeability of electron shuttles is a limiting factor that restricts the electron shuttle‐mediated extracellular electron transfer (EET) from bacteria to electrodes, thus the electricity power output of MFCs. To this end, we heterologously expressed a porin protein OprF from Pseudomonas aeruginosa PAO1 into Escherichia coli, which dramatically increased its membrane permeability, delivering a much higher current output in MFCs than its parental strain (BL21). We found that the oprF‐expression strain showed more efficient EET than its parental strain. More strikingly, the enhanced membrane permeability also rendered the oprF‐expression strain an efficient usage of riboflavin as the electron shuttle, whereas its parental strain was incapable of. Our results substantiated that membrane permeability is crucial for the efficient EET, and indicated that the expression of synthetic porins could be an efficient strategy to enhance bioelectricity generation by microorganisms (including electrogenic bacteria) in MFCs. Biotechnol. Bioeng. 2013; 110: 408–416. © 2012 Wiley Periodicals, Inc.
Age‐ and disease‐related features of task‐related brain oscillations by using mutual information
Authors: Liu Chia‐Ju , Huang Chin‐Fei , Chou Chia‐Yi , Kuo Wen‐jin , Lin Yu‐Te , Hung Chao‐Ming , Chen Tsung‐Ching , Ho Ming‐Chung 
Published: September 2012

AbstractThe aim of this study was to investigate changes in task‐related brain oscillations and corticocortical connections in patients with mild cognitive impairment (MCI) and those with normal aging using cross‐mutual information (CMI) analysis. We hypothesized that task‐related brain oscillations and corticocortical connections were affected by age‐ and disease‐related changes, which could be reflected in the CMI analysis. Electroencephalogram (EEG) recordings were measured in 16 MCI patients, 15 healthy age‐matched controls, and 16 healthy younger individuals. The frequencies and interhemispheric CMI data were estimated in all groups. The specific EEG rhythms measured were delta (δ), theta (θ), alpha (α), beta (β), and gamma (γ) bands. Significant differences in δ, θ, α, and β bands were observed between the younger and elderly groups. However, only the θ band was significantly different between the elderly and MCI groups. Moreover, this study used EEG recordings to investigate age‐ and disease‐related changes in the corticocortical connections of the brain. This study proves that the θ‐band frequency of the connection between the parietal and occipital lobes for the age‐ and disease‐related changes can be depicted using the CMI analysis.
A pH‐Based High‐Throughput Assay for Transketolase: Fingerprinting of Substrate Tolerance and Quantitative Kinetics
Authors: Yi Dong , Devamani Titu , Abdoul‐Zabar Juliane , Charmantray Franck , Helaine Virgil , Hecquet Laurence , Fessner Wolf‐Dieter 
Published: September 2012

AbstractA pH‐based high‐throughput assay method has been developed for the rapid and reliable measurement of transketolase (TK) activity. The method is based on the decarboxylation of lithium hydroxypyruvate (HPA) as a hydroxyacetyl donor with an aldehyde acceptor, using phenol red as the pH indicator. Upon release of carbon dioxide from HPA, the pH increase in the reaction mixture can be determined photometrically by the color change of the pH indicator. At low buffer concentration (2 mM triethanolamine, pH 7.5), the method is highly sensitive and allows continuous monitoring, for quantitative determination of the kinetic parameters. By using this method, the substrate specificities of the TK enzymes from Escherichia coli and Saccharomyces cerevisiae, as well as two active‐site‐modified variants of the E. coli TK (D469E, H26Y) were evaluated against a panel of substrate analogues; specific activities and kinetic constants could be rapidly determined. Substrate quality indicated by assay determination was substantiated with novel TK applications by using achiral 3‐hydroxypropanal and 4‐hydroxybutanal for preparative synthesis of chiral deoxyketose‐type products. Determination of ee for the latter could be performed by chiral GC analysis, with an unambiguous correlation of the absolute configuration from rotation data. This pH‐based assay method is broadly applicable and allows rapid, sensitive, and reliable screening of the substrate tolerance of known TK enzymes and variants obtained from directed evolution.
Studies Related to Norway Spruce Galactoglucomannans: Chemical Synthesis, Conformation Analysis, NMR Spectroscopic Characterization, and Molecular Recognition of Model Compounds
Authors: Ekholm Filip S. , Ardá Ana , Eklund Patrik , André Sabine , Gabius Hans‐Joachim , Jiménez‐Barbero Jesús , Leino Reko 
Published: September 2012

AbstractGalactoglucomannan (GGM) is a polysaccharide mainly consisting of mannose, glucose, and galactose. GGM is the most abundant hemicellulose in the Norway spruce (Picea abies), but is also found in the cell wall of flax seeds, tobacco plants, and kiwifruit. Although several applications for GGM polysaccharides have been developed in pulp and paper manufacturing and the food and medical industries, attempts to synthesize and study distinct fragments of this polysaccharide have not been reported previously. Herein, the synthesis of one of the core trisaccharide units of GGM together with a less‐abundant tetrasaccharide fragment is described. In addition, detailed NMR spectroscopic characterization of the model compounds, comparison of the spectral data with natural GGM, investigation of the acetyl‐group migration phenomena that takes place in the polysaccharide by using small model compounds, and a binding study between the tetrasaccharide model fragment and a galactose‐binding protein (the toxin viscumin) are reported.
Construction of Chlorosomal Rod Self‐Aggregates in the Solid State on Any Substrates from Synthetic Chlorophyll Derivatives Possessing an Oligomethylene Chain at the 17‐Propionate Residue
Authors: Shoji Sunao , Hashishin Takeshi , Tamiaki Hitoshi 
Published: September 2012

AbstractChlorosomes are one of the most unique natural light‐harvesting antennas and their supramolecular nanostructures are still under debate. Chlorosomes contain bacteriochlorophyll (BChl)‐c, d and e molecules and these pigments self‐aggregate under a hydrophobic environment inside a chlorosome. The self‐aggregates are mainly constructed by the following three interactions: hydrogen bonding, coordination bonding and π–π stacking. Supramolecular nanostructures of self‐aggregated BChls have been widely investigated by spectroscopic and microscopic techniques. Model compounds of such chlorosomal BChl molecules have been synthesized and the effects of esterified long alkyl chains at the 17‐propionate residue for their self‐aggregation have been studied. Structurally simple zinc chlorophyll derivatives possessing an oligomethylene chain as the esterifying group at the 17‐propionate residue were prepared as chlorosomal BChl models. The synthetic zinc BChls self‐aggregated in nonpolar organic solvents to give precipitates. The resulting insoluble self‐aggregated solids were investigated on a variety of substrates, including hydrophobic, neutral and hydrophilic substrates, by visible absorption, circular dichroism and polarized light absorption spectroscopies, as well as atomic force, transmission electron and scanning electron microscopies. The self‐aggregates of synthetic Zn‐BChls formed rods with an approximately 5 nm diameter and wires with further elongated growth of the rods (aspect ratio >200). The diameter size was consistent with that estimated for natural chlorosomal rods in a filamentous anoxygenic phototroph, Chloroflexus aurantiacus. The supramolecular formation and stability of the rod on the examined substrates depended on the length of an oligomethylene chain at the 17‐propionate residue as well as on the surface properties. Especially, the number of the 5 nm rods on the substrates increased with an elongation of the chain.
Enantiomeric Specificity of Biologically Significant Cu(II) and Zn(II) Chromone Complexes Towards DNA
Authors: Arjmand Farukh , Jamsheera A. , Afzal Mohd. , Tabassum Sartaj 
Published: September 2012

ABSTRACTNovel chiral Schiff base ligands (R)/(S)‐2‐amino‐3‐(((1‐hydroxypropan‐2‐yl)imino)methyl)‐4H‐chromen‐4‐one (L1 and L2) derived from 2‐amino‐3‐formylchromone and (R/S)‐2‐amino‐1‐propanol and their Cu(II)/Zn(II) complexes (R1, S1, R2, and S2) were synthesized. The complexes were characterized by elemental analysis, infrared (IR), hydrogen (1H) and carbon (13C) nuclear magnetic resonance (NMR), electrospray ionization‐mass spectra (ESI‐MS), and molar conductance measurements. The DNA binding studies of the complexes with calf thymus were carried out by employing different biophysical methods and molecular docking studies that revealed that complexes R1 and S1 prefers the guanine–cytosine‐rich region, whereas R2 and S2 prefers the adenine–thymine residues in the major groove of DNA. The relative trend in Kb values followed the order R1  S1  R2  S2. This observation together with the findings of circular dichroic and fluorescence studies revealed maximal potential of (R)‐enantiomeric form of complexes to bind DNA. Furthermore, the absorption studies with mononucleotides were also monitored to examine the base‐specific interactions of the complexes that revealed a higher propensity of Cu(II) complexes for guanosine‐5′‐monophosphate disodium salt, whereas Zn(II) complexes preferentially bind to thymidine‐5′‐monophosphate disodium salt. The cleavage activity of R1 and R2 with pBR322 plasmid DNA was examined by gel electrophoresis that revealed that they are good DNA cleavage agents; nevertheless, R1 proved to show better DNA cleavage ability. Topoisomerase II inhibitory activity of complex R1 revealed that the complex inhibits topoisomerase II catalytic activity at a very low concentration (25 μM). Furthermore, in vitro antitumor activity of complexes R1 and S1 were screened against human carcinoma cell lines of different histological origin. Chirality 24:977–986, 2012. © 2012 Wiley Periodicals, Inc.
Noncovalent Immobilization of Ionic‐tagged Box‐Cu(OAc)2 Complex and Its Application in Asymmetric Henry Reaction
Authors: Li Zhi‐Huai , Zhou Zhi‐Ming , Hao Xiao‐Yan , Zhang Jun , Dong Xiao , Liu Ying‐Qiang 
Published: September 2012

ABSTRACTImmobilized Cu(OAc)2‐bis(oxazolines) via hydrogen bonding by SBA‐15 was applied to asymmetric Henry reaction, and good enantioselectivities were obtained (up to 83% ee) between 2‐methoxybenzaldehyde and CH3NO2 in isopropyl alcohol (iPrOH). The catalyst could be reused seven times without any obvious loss in enantioselectivity. For the first time, this facile and clean immobilization method is applied to the use of bis(oxazolines) complexes. Chirality 24:1092‐1095, 2012. © 2012 Wiley Periodicals, Inc.
Stereoselective Interaction Between Tetrahydropalmatine Enantiomers and CYP Enzymes in Human Liver Microsomes
Authors: Sun Si‐Yuan , Wang Yu‐Qing , Li Li‐Ping , Wang Lu , Zeng Su , Zhou Hui , Jiang Hui‐Di 
Published: September 2012

ABSTRACTTetrahydropalmatine (THP), with one chiral center, is an alkaloid that possesses analgesic and many other pharmacological actives. The aim of the present study is to investigate stereoselective metabolism of THP enantiomers in human liver microsomes (HLM) and elucidate which cytochrome P450 (CYP) isoforms contribute to the stereoselective metabolism in HLM. Additionally, the inhibitions of THP enantiomers on activity of CYP enzymes are also investigated. The results demonstrated that (+)‐THP was preferentially metabolized by HLM. Ketoconazole (inhibitor of CYP3A4/5) inhibited metabolism of (−)‐THP or (+)‐THP at same degree, whereas the inhibition of fluvoxamine (inhibitor of CYP1A2) on metabolism of (+)‐THP was greater than that of (−)‐THP; moreover, the metabolic rate of (+)‐THP was 5.3‐fold of (−)‐THP in recombinant human CYP1A2. Meanwhile, THP enantiomers did not show obvious inhibitory effect on the activity of various CYP isoforms (CYP1A2, 2A6, 2C8, 2C9, 2C19, 2E1, and 3A4/5), whereas (−)‐THP, but not (+)‐THP, significantly inhibited the activity of CYP2D6 with the Ki value of 6.42 ± 0.38 μM. The results suggested that THP enantiomers were predominantly metabolized by CYP3A4/5 and CYP1A2 in HLM, and (+)‐THP was preferentially metabolized by CYP1A2, whereas CYP3A4/5 contributed equally to metabolism of (−)‐THP or (+)‐THP. Besides, the inhibition of CYP2D6 by (−)‐THP may cause drug–drug interaction, which should be considered. Chirality 25:43–47, 2013. © 2012 Wiley Periodicals, Inc.
A new kinetic model for pyrolysis of Athabasca bitumen
Authors: Kapadia Punitkumar R. , Kallos Michael S. , Gates Ian D. 
Published: September 2012

AbstractPyrolysis of bitumen is a key contributor to gas production in in situ combustion and in situ gasification recovery processes, yet a detailed reaction scheme, that includes a breakdown of products into the most abundant gas components, that is simple enough to be used in detailed thermal‐reactive simulation models, does not exist. Here, we present a novel reaction scheme for pyrolysis of Athabasca bitumen that was developed and calibrated against four experimental data sets (65 data points) over a temperature range from 130 to 422°C. The new model was then verified by comparing its thermogravimetric behaviour against published literature. © 2012 Canadian Society for Chemical Engineering
Common vulnerabilities of RTO implementations in real chemical processes
Authors: Quelhas André D. , de Jesus Normando José Castro , Pinto José Carlos 
Published: September 2012

AbstractReal‐time optimisation (RTO) systems face challenging scenarios in industrial practice, such as incomplete and corrupted process information, uncertain large‐scale mathematical models and numerical optimisation issues. Proper design of RTO structure and robust diagnosis tools are keys for good performance, although they are neglected in commercial RTO software and not fully solved in the technical literature. This article reviews the concepts behind the two‐step RTO approach and suggests performance metrics. It also points out the large list of structural decisions and the consequences of intuitive, experience‐based RTO design choices. The discussed vulnerabilities are illustrated with some simulations and real industrial implementations. © 2012 Canadian Society for Chemical Engineering
Intrapericardial Mature Cystic Teratoma in an Adult: Case Presentation
Authors: Cohen Ronny , Mirrer Brooks , Loarte Pablo , Navarro Victor 
Published: September 2012

AbstractCardiac Teratoma is a tumor of very rare occurrence in adult population. Here we report a case in a Caucasian male with history of Human immunodeficiency virus infection where the symptom as presentation was recurrent episodes of tachycardia. The chest radiograph showed a lesion in the right heart border and subsequent investigation revealed an intrapericardial lesion, which was demonstrated to be a pericardial teratoma diagnosed by histopathology.In this case the initial differential diagnosis included lymphoma or an infectious organism as possible causes in a immunocompromised patient. Cardiac teratomas are among the less common types of cardiac tumors being more frequent in child population and around 1% of all the cardiac tumors in adults. Imaging studies are very helpful. CT and MRI are the best due to their resolution and ability to assess the relationship of the mass with the surrounding structures. Echocardiogram in also helpful determining the presence of pericardial effusion because cardiac teratomas are most of the time present in the pericardium. The final diagnosis is mostly made after surgical excision and this is the most effective treatment because they are relatively resistant to chemotherapy and radiotherapy.The authors have no funding, financial relationships, or conflicts of interest to disclose.
Variation of wavelet entropy in electroencephalogram signal during neurofeedback training
Authors: Ghoshuni Majid , Firoozabadi Mohammad , Khalilzadeh Mohammad Ali , Hashemi Golpayegani Mohammad Reza 
Published: September 2012

AbstractNeurofeedback training (NFT) has an important role in improvement of cognitive functions in both clinical and healthy individuals. In this study, variation of wavelet entropy during low beta NFT was investigated. To investigate the effect of low beta NFT on wavelet entropy, correlation between the change in low beta activity and the change in wavelet entropy was computed. The results revealed that there is a highly significant negative correlation between the change in low beta activity and wavelet entropy. The given outcome suggests that enhancing low beta activity through NFT associated with decrements in wavelet entropy. Furthermore, we discuss a new implementation of NFT, based on wavelet entropy for future research. © 2012 Wiley Periodicals, Inc. Complexity, 2012
Complexity and information: Measuring emergence, self‐organization, and homeostasis at multiple scales
Authors: Gershenson Carlos , Fernández Nelson 
Published: September 2012

AbstractConcepts used in the scientific study of complex systems have become so widespread that their use and abuse has led to ambiguity and confusion in their meaning. In this article, we use information theory to provide abstract and concise measures of complexity, emergence, self‐organization, and homeostasis. The purpose is to clarify the meaning of these concepts with the aid of the proposed formal measures. In a simplified version of the measures (focusing on the information produced by a system), emergence becomes the opposite of self‐organization, while complexity represents their balance. Homeostasis can be seen as a measure of the stability of the system. We use computational experiments on random Boolean networks and elementary cellular automata to illustrate our measures at multiple scales. © 2012 Wiley Periodicals, Inc. Complexity, 2012