bluuebunny/crossref_metadata_2025_split huggingface dataset:
Of circles, forks and humanity: Topological organisation and replication of mammalian mitochondrial DNA
Authors: Pohjoismäki Jaakko L. O. , Goffart Steffi 
Published: February 2011

AbstractThe organisation of mammalian mitochondrial DNA (mtDNA) is more complex than usually assumed. Despite often being depicted as a simple circle, the topology of mtDNA can vary from supercoiled monomeric circles over catenanes and oligomers to complex multimeric networks. Replication of mtDNA is also not clear cut. Two different mechanisms of replication have been found in cultured cells and in most tissues: a strand‐asynchronous mode involving temporary RNA coverage of one strand, and a strand‐coupled mode rather resembling conventional nuclear DNA replication. In addition, a recombination‐initiated replication mechanism is likely to be associated with the multimeric mtDNA networks found in human heart. Although an insight into the general principles and key factors of mtDNA organisation and maintenance has been gained over the last few years, there are many open questions regarding replication initiation, termination and physiological factors determining mtDNA organisation and replication mode. However, common themes in mtDNA maintenance across eukaryotic kingdoms can provide valuable lessons for future work.
Ceftriaxone ameliorates cyclosporine A‐induced oxidative nephrotoxicity in rat
Authors: Yılmaz Nigar , İlhan Selçuk , Nazıroğlu Mustafa , Oktar Süleyman , Nacar Ahmet , Arıca Vefik , Tutanç Murat 
Published: February 2011

AbstractA growing body of evidence now suggested that cyclosporine A (CycA)‐induced nephrotoxicity is a crucial clinical problem and oxidative stress is importantly responsible for its toxicity. Ceftriaxone induced antioxidant effect in brain and neuronal tissues against oxidative damage although its antioxidant potential effect on kidney has not been clarified. The aim of this study was to evaluate whether ceftriaxone protects CycA‐induced oxidative stress kidney injury in rats. Twenty‐four rats were equally divided into four groups. First group was used as control. Ceftriaxone (200 mg/kg) and CycA (15 mg/kg) were administrated to second and third groups for 10 days, respectively. The ceftriaxone and CycA combination was given to rats constituting the fourth group for 10 days. Lipid peroxidation (LP), urea nitrogen and lactate dehydrogenase (LDH) levels were higher in CycA group than in control and ceftriaxone groups although LP, urea nitrogen and LDH levels were lower in ceftriaxone + CycA group than in control and ceftriaxone groups. Glutathione peroxidase and catalase activities were lower in CycA group than in control whereas their activities were increased in control and ceftriaxone groups. Superoxide dismutase activity did not change by the treatments. Ceftriaxone administration recovered also CycA‐induced atrophy, vacuolization and exfoliations of tubular epithelium and glomerular collapse in histopathological evaluation of kidney. In conclusion, we observed that ceftriaxone is beneficial on CycA‐induced oxidative stress in kidney of rats by modulating oxidative and antioxidant system. Copyright © 2011 John Wiley & Sons, Ltd.
Induction of MiR‐17‐3p and MiR‐160a by TNFα and LPS
Authors: Jiang Xin , Li Nancy 
Published: February 2011

AbstractMicroRNAs (miRNAs), small non‐coding molecules, regulate gene expression in response to stimuli. Lipopolysaccharide (LPS) was reported to induce the expression of miR‐146 and miR‐155 in HL‐60. The effects of LPS and the related stimulus, tumour necrosis factor alpha (TNFα), on miRNA expression required to be further studied. Using T7‐oligo ligation assay (OLA)‐based miRNA array, we profiled the expression of 132 miRNAs and identified a number of TNFα‐regulated miRNAs in HeLa cells, including miR‐17‐3p and miR‐106a. TNFα induction of miR‐17‐3p and miR‐106a was verified by Northern blot analysis with RNU48 normalization. Northern blot analysis also showed that LPS was able to induce the expression of both miR‐17‐3p and miR‐106a in HeLa cells. Furthermore, both array assay and Northern blot analysis showed that the expression levels of miR‐146 and miR‐155 were either low or undetectable in HeLa cells and TNFα‐ and LPS‐mediated induction of these two miRNAs was not found. Luciferase reporter analysis confirmed the induction of miR‐17‐3p and miR‐106a in response to TNFα and LPS treatment in HeLa cells. These results suggested that the expression of miR‐17‐3p and miR‐106a is regulated by TNFα and LPS in HeLa cells. Copyright © 2011 John Wiley & Sons, Ltd.
Effect of ubiquitin carboxy‐terminal hydrolase 37 on apoptotic in A549 cells
Authors: Chen Zhiwei , Niu Xiaomin , Li Ziming , Yu Yongfeng , Ye Xiangyun , Lu Shun , Chen Zhen 
Published: February 2011

AbstractProteins destined for degradation by the ubiquitin‐proteasome system are labelled with a 76‐amino acid peptide, ubiquitin, through a series of conjugation steps by the E1, E2 and E3 enzymes respectively. Ubiquitin carboxy‐terminal hydrolase 37 (UCH37) belongs to the UCH proteases family that deubiquitinates ubiquitin‐protein conjugates in the ubiquitin‐proteasome system. However, it is few reports about the relationship between UCH37 and apoptosis. In order to clarify the role of UCH37 on apoptosis, the A549 cells were chosen for this study. We transfected UCH37 siRNA and pcDNA3.1‐UCH37 plasmid into A549 cells, respectively. Using MTT assay, Western blot, Hoechst 33342 staining assay and flow cytometry, we found that silencing of UCH37 in A549 cells induced apoptosis. The ratio of Bax/Bcl‐2 was higher in silencing of UCH37 than that in control group after silencing of UCH37 in A549 cells. Meanwhile, experiments with the A549 cell line disclose that silencing of UCH37 could induce efficiently A549 cell apoptosis through activation of caspase‐9 and caspase‐3. On the other hand, over‐expression of UCH37 led to the opposite effect. Hence, UCH37 might play an important role in apoptotic through altering Bax/Bcl‐2 ratio and enzymatic activities of caspase‐9 and caspase‐3. Copyright © 2011 John Wiley & Sons, Ltd.
In‐line monitoring of Saccharomyces cerevisiae fermentation with a fluorescence probe: new approaches to data collection and analysis
Authors: Bogomolov Andrey , Grasser Thorsten , Hessling Martin 
Published: February 2011

AbstractFluorescence analysis, in particular two‐dimensional excitation‐emission matrix (EEM) spectroscopy, is a sensitive in‐line process monitoring tool in the biotechnological production. Before it can be widely adopted by the industry, fast effective algorithms for the analysis of massive and complex fluorescence data should be developed. Weak emission signals are prone to various interferences complicating the modeling, such as excitation light Rayleigh scatter. The scatter is usually considered as an unwanted background to be avoided or removed.This work is focused on effective usage of the entire spectral information. It has been shown that scatter peaks coming from the excitation or an external light source can be used in the data analysis to improve the performance of a multivariate model. A new fluorescence Lighthouse Probe™ (LHP) has been applied in‐line to monitor Saccharomyces cerevisiae fermentation in a lab reactor. Exploratory data analysis of two fed‐batch cultivations has been performed using Partial Least Squares regression and Multivariate Curve Resolution. A simple algorithm for the resolution of process profiles and two‐dimensional spectra of individual fluorophores from three‐way fluorescence data in the presence of intensive scatter has been suggested and applied to the process diagnostics. Copyright © 2011 John Wiley & Sons, Ltd.
Molybdenum‐Catalyzed Asymmetric Allylic Alkylation of 3‐Alkyloxindoles: Reaction Development and Applications
Authors: Trost Barry M. , Zhang Yong 
Published: February 2011

AbstractWe report a full account of our work towards the development of Mo‐catalyzed asymmetric allylic alkylation reactions with 3‐alkyloxindoles as nucleophiles. The reaction is complementary to the Pd‐catalyzed reaction with regard to the scope of oxindole nucleophiles. A number of 3‐alkyloxindoles were alkylated successfully under mild conditions to give products with excellent yields and good‐to‐excellent enantioselectivities. Applications of this method to the preparation of indoline alkaloids such as (−)‐physostigmine, ent‐(−)‐debromoflustramine B, and the indolinoquinoline rings of communesin B are reported.
Kinetic and Theoretical Studies on Alkaline Ethanolysis of 4‐Nitrophenyl Salicylate: Effect of Alkali Metal Ions on Reactivity and Mechanism
Authors: Um Ik‐Hwan , Seo Jin‐A , Mishima Masaaki 
Published: February 2011

AbstractPseudo‐first‐order rate constants (kobsd) for reactions of 4‐nitrophenyl salicylate (7) with alkali metal ethoxides (EtOM, M=K, Na, and Li) in anhydrous ethanol have been measured spectrophotometrically. Interestingly, the kobsd value decreases significantly as the concentration of EtOM increases. Because the phenolic moiety of substrate 7 would be deprotonated and exist as an anionic form (i.e., 7−) under kinetic conditions, the ground‐state stabilization of 7− through formation of a six‐membered cyclic complex with M+ (i.e., 8) is proposed to be responsible for the decreasing kobsd trend. The kobsd value at a given concentration of EtOK increases steeply upon addition of [18]crown‐6 ether (18C6) up to [18C6]/[EtOK]=1 in the reaction mixture and then remains relatively constant thereafter. In contrast, kobsd decreases upon addition of salts (e.g., LiClO4 or KSCN) to the reaction mixture, which indicates that M+ ions inhibit the reaction. However, in the presence of 18C6, the kobsd value is independent of the concentration of EtOK but remains constant, which indicates that the reaction proceeds through a unimolecular mechanism in the presence of the complexing agent. Although two conceivable unimolecular pathways (formation of ketene 9 and lactone 10) can account for the kinetic results, the reaction has been concluded to proceed via formation of ketene 9 as the reactive intermediate on the basis of theoretical calculations.
Haloperoxidase Activity of Oxovanadium(V) Thiobisphenolates
Authors: Werncke C. Gunnar , Limberg Christian , Knispel Christina , Metzinger Ramona , Braun Beatrice 
Published: February 2011

AbstractBy employing the 2,2′‐thiobis(2,4‐di‐tert‐butylphenolate) ligand (SL2−) a novel oxovanadium(V) complex, (PPh4)2[SLV(O)(μ2‐O)2V(O)SL] (1), was synthesised that exhibits haloperoxidase activity: on addition of H2O2 a sequence of successive peroxide formation and intramolecular thioether oxidation events (sulfoxide and sulfone) led to a mixture of five products, which were all identified unambiguously, partly through an independent synthesis and characterisation. It was shown that internal thioether oxidation proceeds through peroxide formation, but the sulfoxidation of external thioether functions requires further activation of the peroxide function by protons or alkyl cations. Consistently, the employment of tBuOOH instead of H2O2 led to a very active system for the catalytic sulfoxidation of thioethers.
Das kalte Licht der Olefine
Authors: Albrecht Steffen , Brandl Herbert , Ciscato Luiz Frazisco Monteiro Leite , Weiß Dieter , Augustin Dieter , Zimmermann Thomas 
Published: February 2011

AbstractDer folgende Artikel setzt die Reihe unserer ChiuZ‐Beiträge zur Chemi‐ und Biolumineszenz mit einer interessanten und neuen experimentellen Arbeit zum “kalten Licht” spezieller ungesättigter Verbindungen fort, deren Anwendung auch in der modernen Zeit der Nanotechnologie im biochemischen bzw. medizinisch‐chemischen Labor völlig neue Akzente gesetzt hat.
Was verbindet zelluläre Virusabwehr und Vesikeltransport?
Authors: Hille‐Rehfeld Annette 
Published: February 2011

AbstractVirale Krankheitserreger können auch bei der Erstinfektion schnell außer Gefecht gesetzt werden. Im Rahmen der angeborenen Immunantwort der Wirbeltiere werden dafür – ausgelöst durch den Immunmediator Interferon – in infizierten Zellen Resistenzproteine gebildet, die eingedrungene Viren an der Vermehrung hindern. Myxovirus‐Resistenzproteine beispielsweise schützen vor einem weiten Spektrum an RNA‐ und DNA‐Viren einschließlich Influenza A, B und C. Sie gehören zur Proteinfamilie der Dynamin‐GTPasen. Das namensgebende Dynamin ist ein membranassoziiertes Protein, das die Bildung von Membranvesikeln des intrazellulären Transports unterstützt. Ein Strukturmodell des humanen Myxovirus‐Resistenzprotein1 lieferte jetzt eine Vorstellung von den molekularen Grundlagen der Virusabwehr.
Cyclopentadienyl‐Analoga mit Bor und Blei
Authors: Jaenicke Lothar 
Published: February 2011

AbstractDie Cyclopentadien‐Chemie sorgt immer wieder für Überraschungen. Die Hückel‐Frage nach dem aromatischen Zustand der Metallole ist nicht zum Ende des Periodischen Systems durchdiskutiert, und auch ganz am Anfang stehen mit den Borolen noch immer neue Perspektiven.
Eine vollsynthetische Diels‐Alderase
Authors: Harrer Rowitha 
Published: February 2011

AbstractPasst, quietscht, sitzt und hat Luft: Um den Übergangszustand der wichtigen Diels‐Alder‐Reaktion herum wurde das aktive Zentrum eines neuen Enzyms maßgeschneidert. Zum ersten Mal wurde für eine solch anspruchsvolle Reaktion ein Enzym von Grund auf modelliert, hergestellt und getestet.
Real‐time 3D MRI of contrast agents in whole living mice
Authors: Bled Emilie , Hassen Wadie Ben , Pourtau Line , Mellet Philippe , Lanz Titus , Schüler Dorothee , Voisin Pierre , Franconi Jean‐Michel , Thiaudière Eric , Miraux Sylvain 
Published: February 2011

AbstractA specific mouse whole body coil and a dedicated gradient system at 4.7 T were coupled with an ultra‐fast 3D gradient echo MRI and keyhole reconstruction technique to obtain 3D whole‐body dynamic T1‐weighted or T2*‐weighted imaging. The technique was used to visualize the real‐time distribution of non‐targeting T1 and T2* contrast agent (CA) in a glioma‐bearing mouse model. T1 dynamic contrast‐enhancement imaging was performed with a fast imaging with steady‐state precession sequence [echo time/repetition time (TE/TR), 1.32/3.7 ms] before and after CA injection (Gd–DOTA and BSA–Gd–DOTA) for 21 min. The temporal resolution was 1 image/6.5 s. T2* imaging (TE/TR, 4/8 ms) was performed before and after iron‐based (small and ultra‐small particles of iron oxide) CA injection for 45 min. The temporal resolution was 1 image/14 s. Signal‐to‐noise ratio curves were determined in various mouse organs. The whole‐body coil and gradient systems made it possible to acquire data with sufficient and homogeneous signal‐to‐noise ratio on the whole animal. The spatial resolution allowed adequate depiction of the major organs, blood vessels and brain glioma. The distribution and the time‐course of T1 and T2* contrasts upon contrast agent injection were also assessed. 3D whole‐body mouse MRI is feasible at high spatial resolution in movie mode and can be applied successfully to visualize real‐time contrast agent distribution. This method should be effective in future preclinical molecular imaging studies. Copyright © 2011 John Wiley & Sons, Ltd.
Influence of tempereature on Struvite precipitation by CO2‐deagassing method
Authors: Ben Moussa S. , Tlili M. M. , Batis N. , Amor M. Ben 
Published: February 2011

AbstractThe present study explores struvite precipitation by degassing method under different temperature (14.5‐35 °C). It is shown that an increase of temperature does not affect the nucleation kinetics but strongly influences the growth rate and the efficiency of the phosphate removal. This was attributed to the effect of temperature on the struvite solubility and then the reached supersaturation coefficient. It was also shown, by using degassing method, that the determined solubility constant (pKs) values of struvite, at 14.5, 20, 25 and 35 °C are 13.00, 12.82, 12.63 and 13.20, respectively, are close to those presented in the literature. The results show that temperature influences the kinetics of precipitation. First‐order kinetics were found to be sufficient to describe the rate data. The rates decreased with increasing temperature and the apparent rate constants for the reaction were determined. Arrhenius plots yielded a relatively apparent high activation energy Ea = 31.0 kJ·mol–1. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of methyloxime derivatives of intact esters of testosterone and boldenone in equine plasma using ultra high performance liquid chromatography tandem mass spectrometry
Authors: Gray Bobby P. , Teale Phil , Pearce Clive M. 
Published: February 2011

AbstractAnalysis of equine plasma samples to detect the abuse of anabolic steroids can be complicated when the parent steroid is endogenous to the animal. Anabolic steroids are usually administered intramuscularly as synthetic esters and therefore detection of the exogenous esters provides unequivocal proof of illegal administration. An ultra high performance liquid chromatography tandem mass spectrometric (UPLC‐MSMS) method for the analysis of esters of testosterone (propionate, phenylpropionate, isocaproate, and decanoate) and boldenone (undecylenate) in equine plasma has been developed. Esters were extracted from equine plasma using a mixture of hexane and ethyl acetate and treated with methoxyamine hydrochloride to form methyloxime derivatives. Metenolone enanthate was used as an internal standard. After chromatographic separation, the derivatized steroid esters were quantified using selected reaction monitoring (SRM). The limit of detection for all of the steroid esters, based on a signal to noise ratio (S/N) of 3:1, was 1–3 pg/mL. The lower limit of quantification (LLOQ) for the all of the steroid esters was 5 pg/mL when 2 mL of plasma was extracted. Recovery of the steroid esters was 85–97% for all esters except for testosterone decanoate which was recovered at 62%. The intra‐day coefficient of variation (CV) for the analysis of plasma quality control (QC) samples was less than 9.2% at 40 pg/mL and less than 6.0% at 400 pg/mL. The developed assay was used to successfully confirm the presence of intact testosterone esters in equine plasma samples following intramuscular injection of Durateston® (mixed testosterone esters). Copyright © 2011 John Wiley & Sons, Ltd.
Tailor‐Made Modification of a Gold Surface for the Chemical Binding of a High‐Activity [FeFe] Hydrogenase
Authors: Krassen Henning , Stripp Sven T. , Böhm Nadine , Berkessel Albrecht , Happe Thomas , Ataka Kenichi , Heberle Joachim 
Published: February 2011

AbstractHydrogenases are iron–sulfur proteins that catalyze hydrogen turnover in a wide range of microorganisms. Three different classes have been described, and among these [FeFe] hydrogenases are the most active in H2 evolution. Hydrogenases are redox enzymes that have been shown to exchange electrons with graphite and modified noble metal electrodes. Making use of the latter, diffusible electron carriers are required to enable redox catalysis, as proteins do not specifically bind to the electrode surface. Diffusion‐limited electron transfer can be replaced by electron injection into immobilized hydrogenase by binding the redox mediator to the electrode surface. Here, we present the synthesis and spectroelectrochemical characterization of 1‐(10‐mercaptodecyl)‐1′‐benzyl‐4,4′‐bipyridinium dibromide (MBBP), which is used as redox‐active linker. CrHydA1, the high‐activity [FeFe] hydrogenase from Chlamydomonas reinhardtii, is immobilized on the linker‐modified gold electrode. Each surface modification step is controlled in situ by surface‐enhanced infrared absorption spectroscopy (SEIRAS). Functionality of the electrode–protein hybrid is demonstrated by recording the linker‐supported current. The specificcatalytic rate of hydrogen evolution by CrHydA1 (2.9 μmol H2 min–1 mg–1 hydrogenase) promises a valuable approach for further optimization of this novel bioelectrical interface.
AC field induced‐charge electroosmosis over leaky dielectric blocks embedded in a microchannel
Authors: Zhao Cunlu , Yang Chun 
Published: February 2011

AbstractAn effective electrical boundary condition is formulated to describe AC field‐driven induced‐charge electrokinetic (ICEK) phenomena at the interface between a liquid and a leaky dielectric solid. Since most materials in reality possess finite dielectric and conductive properties, i.e. leaky dielectric, the present boundary condition can be used to describe the induced zeta potential on a leaky dielectric surface with consideration of both bond charges (due to polarization) and free charges (due to conduction). Two well‐known limiting cases, i.e. the perfectly dielectric and the perfectly conducting wall boundary conditions can be recovered from the present formulation. Utilizing the derived boundary condition, we obtain analytical solutions in closed form for the AC field‐driven induced‐charge electroosmosis (ICEO) over two symmetric leaky dielectric blocks embedded in the walls of an infinitely long microchannel. Two important factors for the induced zeta potential are identified to respectively account for the polarization charges and the free charges, and their effects on AC field‐driven ICEO oscillating flow patterns are analyzed. It is found that the flow patterns exhibit two counter‐rotating vortices, which can be deformed, relocated, eliminated and even reverse their rotating directions. It is very promising that such temporary evolution of flow patterns can possibly induce chaotic advection which can enhance microfluidic mixing.
Extracellular alkaline protease from Bacillus licheniformis NCIM‐2042: Improving enzyme activity assay and characterization
Authors: Bhunia Biswanath , Dutta Debjani , Chaudhuri Surabhi 
Published: February 2011

AbstractOptimization of enzyme assay conditions for alkaline protease from Bacillus licheniformis NCIM‐2042 was carried out by a statistical approach. Four key determinants such as pH, temperature, buffer concentration, and incubation time were optimized by response surface methodology using rotatable central composite design. Maximum enzyme activity was found to be at pH 9.0, temperature 75°C in phosphate buffer (50 mM) when incubated for 10 min. Protease was stable over a broad range of pH 6.0–12.0 and it was stable at 50°C for 1 h. The protease was completely inhibited by PMSF (5 mM), suggesting that the enzyme is a serine alkaline protease. This enzyme had good stability in the presence of H2O2, SDS, Triton X‐100, and retained more than 88% of its initial activity after preincubation for 30 min at room temperature in the presence of 25% v/v DMSO, methanol, ethanol, ACN, and 2‐propanol.
Casein and transglutaminase‐mediated modification of wool surface
Authors: Cui Li , Fan Xuerong , Wang Ping , Wang Qiang , Fu Guangtong 
Published: February 2011

AbstractIn this study, casein, a protein found in milk, was used as a surface‐coating material for improving wool fabric properties mediated by a microbial protein cross‐linking enzyme: transglutaminase (TGase). For the wool fabric used in this study, 4% casein (owf) treatment for 1 h combined with 20 U/g fabric of microbial TGase reduced the area shrinkage of the KMnO4‐pretreated wool fabric from 11.32±0.26 to 4.57±0.15%. The tensile strength increased from 275±5.0 to 315±2.1 N. The casein cross‐linked by TGase on wool exhibited better stability than that with the inactivated enzyme in warm water, Na2CO3 and SDS solutions. Scanning electron micrographs demonstrated that the casein and TGase treatment smoothened the wool fiber surface by coating or filling the raised scales of the wool.