bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuroprotective versus neurodestructive effects of NO‐related species
Authors: Lipton Stuart A. , Choi Yun‐Beom , Sucher Nikolaus J. , Chen H.‐S. Vincent 
Published: November 2008

AbstractNitric oxide (NO·) can lead to damaging or protective actions in the central nervous system. Here we consider the chemistry of the NO group and its redox‐related species that can lead to these exactly opposite ends. In the neurodestructive mode, NO· reacts with superoxide anion (O2·−) to form peroxynitrite (ONOO−), which leads to neuronal injury. In contrast, the reaction of the NO group with cysteine sulfhydryls on the NMDA receptor leads to a decrease in receptor/channel activity, avoidance of excessive Ca2+entry, and thus neuroprotection. Site‐directed mutagenesis of recombinant NMDA receptor subunits has recently increased our knowledge of such redox modulation by NO. Transfer of the NO group to cysteine sulfhydryls on the NMDA receptor or other proteins, known as S‐nitrosylation, is becoming recognized as a ubiquitous regulatory reaction, akin to phosphorylation, and represents a form of redox modulation in diverse tissues including the brain.
Experimental diabetic neuropathy: Role of oxidative stress and mechanisms involved
Authors: Martínez‐Blasco Amparo , Bosch‐Morell Francisco , Trenor Carlos , Romero Francisco J. 
Published: November 2008

AbstractOxidative stress has been related to the development of diabetic neuropathy. Experimental diabetes (alloxan injection to mice) promotes early biochemical changes in peripheral nervous tissue, e.g., decrease in Na,K‐ATPase activity and glutathione (GSH) peroxidase (GSHPx) activity. The former decrease can be reverted by inhibiting protein kinase C (PKC), since it has been reported that PKC is activated in these experimental conditions. Here we present data demonstrating that the inhibition of PKC, as early as 4 days after alloxan administration, is not able to return to normal values GSHPx activity in sciatic nerve of diabetic mice. Thus, it would fit with our previous proposal of the possible glycation of this protein as an early event in experimental diabetes, and apparently rules out the control of GSHPx activity by PKC in this tissue.
An ethanolic‐aqueous extract of Curcuma longa decreases the susceptibility of liver microsomes and mitochondria to lipid peroxidation in atherosclerotic rabbits
Authors: Quiles J. L. , Aguilera C. , Mesa M. D. , Ramírez‐Tortosa M. C. , Baró L. , Gil A. 
Published: November 2008

AbstractAtherosclerosis is characterized by oxidative damage which affects lipoproteins, the walls of blood vessels and subcellular membranes. This study evaluates the antioxidant capacity of a Curcuma longa extract on the lipid peroxidation of liver mitochondria and microsome membranes in atherosclerotic rabbits. Male rabbits fed a 3% (w/w) lard and 1.3% (w/w) cholesterol diet were randomly assigned to three groups. Two groups were treated with different dosages of a turmeric extract (A and B) and the third group (control) with a curcumin‐free solution. Basal and in vitro 2,2'‐azobis (2‐amidinopropane) dihydrochloride (AAPH)‐induced hydroperoxide and TBARS productions in liver mitochondria and microsomes were analyzed. Group A had the lowest concentration of mitochondrial hydroperoxides. In microsomes, the basal hydroperoxide levels were similar in all groups but, after the induction of oxidation, group C registered the highest value; TBARS production followed the same trend in mitochondria. These findings suggest that active compounds in curcuma extract may be protective in preventing lipoperoxidation of subcellular membranes in a dosage‐dependent manner.
Ischaemia—reperfusion injury of the liver: treatment in theory and in practice
Authors: Tredger J. Michael 
Published: November 2008

AbstractCold ischaemia—reperfusion injuries are an unavoidable feature of current liver transplantation procedures. Damage to liver grafts accures mainly from hypothermic storage under hypoxic conditions (cold ischaemia), from sustained ischaemia during implantation into the recipient (rewarming ischaemia) and from restoration of blood and oxygen to the graft (reperfusion injury). These three stages are characterized by progressive deteriorations in hepatic function, with sinusoidal endothelial cells most affected during cold ischaemia. Activation of Kupffer cells (hepatic macrophages) at reperfusion augments damage to both endothelial and parenchymal cells by the release of numerous compounds which initiate and perpetrate injury and impair the hepatic microcirculation. The key events in the expression of ischaemia—reperfusion injury are detailed and therapeutic interventions are described which target these steps. The treatments discussed include University of Wisconsin (UW) preservation solution, calcium channel blockade, inhibitors of Kupffer cell activation, promoters of microvascular vasodilatation, hepatoprotectants and the use of anti‐oxidants.
Phagocyte‐induced oxidative stress in patients with haemodialysis treatment and organ transplantation
Authors: Lojek A. , Ĉerný J. , Němec P. , Niĉovský J. , Soška V. , Ĉíž M. , Slavíková H. , Kubala L. 
Published: November 2008

AbstractThe aim of the study was to examine the phagocyte‐derived production of reactive oxygen species (ROS), lipoperoxidation and the total radical‐trapping antioxidant parameter (TRAP) in patients undergoing regular haemodialysis (HD) followed by kidney transplantation (n=13). A significant increase in both spontaneous and activated ROS generation was found during the post‐transplantation period in days 1–3. This effect was caused mainly by an increased number of neutrophils. On the other hand, the TRAP parameter was decreased in HD patients. After kidney transplantation, the TRAP parameter increased, reaching the level of healthy controls at the end of the first week after surgery. Increase in MDA level was determined after HD and kidney transplantation. It can be concluded from the results obtained that phagocyte mobilisation and increased oxidative stress after HD and kidney transplantation were associated with the insufficient activity of extracellular antioxidant mechanisms resulting in increased lipid peroxidation.
Mass‐Spectrometric Identification of Anandamide and 2‐Arachidonoylglycerol in Nematodes
Authors: Lehtonen Marko , Reisner Kaja , Auriola Seppo , Wong Garry , Callaway James C. 
Published: November 2008

AbstractThe purpose of the study was to see if nematodes (Caenorhabditis elegans, Caenorhabditis briggsae, and Pelodera strongyloides) produce endocannabinoids; i.e., anandamide (AEA) and 2‐arachidonoylglycerol (2‐AG). In this study, AEA and 2‐AG were identified as endogenous products from nematodes by using electrospray‐ionization ion‐trap MS/MS (ESI‐IT‐MS) experiments operated in the positive‐ionization mode. Endocannabinoids were identified by product ion scan and concentrations were measured by triple quadrupole mass spectrometry in the multiple reaction monitoring mode (MRM). Both AEA and 2‐AG were identified in all of the nematode samples, even though these species lack known cannabinoid receptors. Neither AEA nor 2‐AG were detected in the fat‐3 mutant of C. elegans, which lacks the necessary enzyme to produce arachidonic acid, the fatty acid precursor of these endocannabinoids.
Total Synthesis of desB30 Insulin Analogues by Biomimetic Folding of Single‐Chain Precursors
Authors: Tofteng A. Pernille , Jensen Knud J. , Schäffer Lauge , Hoeg‐Jensen Thomas 
Published: November 2008

AbstractInsulin is a peptide hormone consisting of 51 amino acids in two chains with three disulfide bridges. Human insulin and various analogues are used for the treatment of diabetes and are produced recombinantly at ton scale. Herein, we report the chemical synthesis of insulin by the step‐wise, Fmoc‐based, solid‐phase synthesis of single‐chain precursors with solubilising extensions, which under redox conditions, spontaneously fold with the correct pairing of the three disulfide bridges. The folded, single‐chain, insulin precursors can be transformed into bioactive two‐chain desB30 insulin by the simultaneous removal of the solubilising extension (4–5 residues) and the chain‐bridging C‐peptide (3–5 residues) by employing Achromobacter lyticus protease—a process well‐known from the yeast‐based recombinant production of insulin. The overall yields of synthetic insulins were as much as 6 %, and the synthetic process was straightforward and not labour intensive.
Cooperative Biosynthesis of Trisporoids by the (+) and (−) Mating Types of the Zygomycete Blakeslea trispora
Authors: Schachtschabel Doreen , David Anja , Menzel Klaus‐Dieter , Schimek Christine , Wöstemeyer Johannes , Boland Wilhelm 
Published: November 2008

AbstractThe fungal phylum zygomycota uses trisporic acids (TSAs), a family of apocarotenoids, during sexual reproduction to synchronize and control activity between the mycelial hyphae of opposite mating types. Separate as well as mixed cultures of Blakeslea trispora were systematically supplemented with putative, deuterium‐labeled precursors downstream of β‐carotene en route to the bioactive TSAs. Analysis of the isolated metabolites allowed the reconstruction of the complete biosynthetic sequence between the first apocarotenoid, D'orenone (1), and the different series of TSAs B (8) and C (13). Both mating types produced a similar spectrum of early metabolites upstream of trisporols B (7) and C (12), while only the (+) type was able to further oxidize trisporols B (7) and C (12) to the corresponding methyltrisporoid B (5) and C (11), respectively. A novel 4‐dihydrotrisporic acid B (14) that was not formed from the labeled precursors was isolated from mated strains; this compound might be derived from oxygenated β‐carotene by a parallel pathway. The ester accumulated in the culture broth of the (+) strain and was only hydrolyzed by mycelia of the (−) strain; this corresponds to a synchronization of the biosynthetic activities of both mating types.
Multi‐block methods in multivariate process control
Authors: Kohonen Jarno , Reinikainen Satu‐Pia , Aaljoki Kari , Perkiö Annikki , Väänänen Taito , Höskuldsson Agnar 
Published: November 2008

AbstractIn chemometric studies all predictor variables are usually collected in one data matrix X. This matrix is then analyzed by PLS regression or other methods. When data from several different sub‐processes are collected in one matrix, there is a possibility that the effects of some sub‐processes may vanish. If there is, for instance, mechanic data from one process and spectral data from another, the influence of the mechanic sub‐process may not be detected. An application of multi‐block (MB) methods, where the X‐data are divided into several data blocks is presented in this study. By using MB methods the effect of a sub‐process can be seen and an example with two blocks, near infra‐red, NIR, and process data, is shown. The results show improvements in modelling task, when a MB‐based approach is used. This way of working with data gives more information on the process than if all data are in one X‐matrix. The procedure is demonstrated by an industrial continuous process, where knowledge about the sub‐processes is available and X‐matrix can be divided into blocks between process variables and NIR spectra. Copyright © 2008 John Wiley & Sons, Ltd.
RNA Aptamers That Reversibly Bind Photoresponsive Azobenzene‐Containing Peptides
Authors: Hayashi Gosuke , Hagihara Masaki , Nakatani Kazuhiko 
Published: November 2008

AbstractModulation of biological networks assembled by diverse interactions among biologically active molecules has provided a platform for innovative biotechnologies. Here, we report RNA aptamers that bind to a photoresponsive peptide (KRAzR; Lys‐Arg‐azobenzene‐Arg) containing azobenzene chromophore, which can change its structure by photoirradiation. Aptamers were identified after 10 cycles of an in vitro selection procedure starting with a DNA library containing a 70 nt random region. Surface plasmon resonance (SPR) analysis demonstrated that interactions between aptamers and KRAzR were fully controlled by appropriate photoirradiation to the SPR sensor chip. Upon irradiation of 360 nm on the KRAzR‐immobilized surface, the binding of each aptamer to the surface was significantly decreased. Subsequent photoirradiation of the same surface with 430 nm restored the aptamer binding to the surface. We also observed that direct photoirradiation of the aptamer–peptide complex on a gold surface actively promoted dissociation of the complex. Furthermore, a doped reselection method was applied to acquire structural and sequence information of aptamer 66. From a data analysis of the conserved region and the mutation frequency, we were able to select a plausible secondary structure among three candidates predicted by computational folding simulation.
Enhancing Intermolecular Benzoyl‐Transfer Reactivity in Crystals by Growing a “Reactive” Metastable Polymorph by Using a Chiral Additive
Authors: Murali Chebrolu , Shashidhar Mysore S. , Gonnade Rajesh G. , Bhadbhade Mohan M. 
Published: November 2008

AbstractRacemic 2,4‐di‐O‐benzoyl‐myo‐inositol‐1,3,5‐orthoacetate, which normally crystallizes in a monoclinic form (form I, space group P21/n) could be persuaded to crystallize out as a metastable polymorph (form II, space group C2/c) by using a small amount of either D‐ or L‐ 2,4‐di‐O‐benzoyl‐myo‐inositol‐1,3,5‐orthoformate as an additive in the crystallization medium. The structurally similar enantiomeric additive was chosen by the scrutiny of previous experimental results on the crystallization of racemic 2,4‐di‐O‐benzoyl‐myo‐inositol‐1,3,5‐orthoacetate. Form II crystals can be thermally transformed to form I crystals at about 145 °C. The relative organization of the molecules in these dimorphs vary slightly in terms of the helical assembly of molecules, that is, electrophile (El)⋅⋅⋅nucleophile (Nu) and CH⋅⋅⋅π interactions, but these minor variations have a profound effect on the facility and specificity of benzoyl‐group‐transfer reactivity in the two crystal forms. While form II crystals undergo a clean intermolecular benzoyl‐group‐transfer reaction, form I crystals are less reactive and undergo non‐specific benzoyl‐group transfer leading to a mixture of products. The role played by the additive in fine‐tuning small changes that are required in the molecular packing opens up the possibility of creating new polymorphs that show varied physical and chemical properties. Crystals of D‐2,6‐di‐O‐benzoyl‐myo‐inositol‐1,3,5‐orthoformate (additive) did not show facile benzoyl‐group‐transfer reactivity (in contrast to the corresponding racemic compound) due to the lack of proper juxtaposition and assembly of molecules.
Direct Zincation of Functionalized Aromatics and Heterocycles by Using a Magnesium Base in the Presence of ZnCl2
Authors: Dong Zhibing , Clososki Giuliano C. , Wunderlich Stefan H. , Unsinn Andreas , Li Jinshan , Knochel Paul 
Published: November 2008

AbstractA wide range of polyfunctional aryl and heteroaryl zinc reagents were efficiently prepared in THF by using (TMP)2Mg⋅2 LiCl (TMP=2,2,6,6‐tetramethylpiperamidyl) in the presence of ZnCl2. The possible pathways of this metalation procedure as well as possible reactive intermediates are discussed. This experimental protocol expands the tolerance of functional groups and allows an efficient zincation of sensitive heterocycles such as quinoxaline or pyrazine. The zincated arenes and heteroarenes react with various electrophiles providing the expected products in 60–95 % yield.
Pyrrolidinium Ionic Liquid Crystals
Authors: Goossens Karel , Lava Kathleen , Nockemann Peter , Van Hecke Kristof , Van Meervelt Luc , Driesen Kris , Görller‐Walrand Christiane , Binnemans Koen , Cardinaels Thomas 
Published: November 2008

AbstractN‐Alkyl‐N‐methylpyrrolidinium cations have been used for the design of ionic liquid crystals, including a new type of uranium‐containing metallomesogen. Pyrrolidinium salts with bromide, bis(trifluoromethylsulfonyl)imide, tetrafluoroborate, hexafluorophosphate, thiocyanate, tetrakis(2‐ thenoyltrifluoroacetonato)europate(III) and tetrabromouranyl counteranions were prepared. For the bromide salts and tetrabromouranyl compounds, the chain length of the alkyl group CnH2n+1 was varied from eight to twenty carbon atoms (n=8, 10–20). The compounds show rich mesomorphic behaviour: highly ordered smectic phases (the crystal smectic E phase and the uncommon crystal smectic T phase), smectic A phases, and hexagonal columnar phases were observed, depending on chain length and anion. This work gives better insight into the nature and formation of the crystal smectic T phase, and the molecular requirements for the appearance of this highly ordered phase. This uncommon tetragonal mesophase is thoroughly discussed on the basis of detailed powder X‐ray diffraction experiments and in relation to the existing literature. Structural models are proposed for self‐assembly of the molecules within the smectic layers. In addition, the photophysical properties of the compounds containing a metal complex anion were investigated. For the uranium‐containing mesogens, luminescence can be induced by dissolving them in an ionic liquid matrix. The europium‐containing compound shows intense red photoluminescence with high colour purity.
Thermal Decomposition Modes for Four‐Coordinate Ruthenium Phosphonium Alkylidene Olefin Metathesis Catalysts
Authors: Leitao Erin M. , Dubberley Stuart R. , Piers Warren E. , Wu Qiao , McDonald Robert 
Published: November 2008

AbstractThe four‐coordinate ruthenium phosphonium alkylidenes 1‐Cy and 1‐iPr, differing in the substituent on the phosphorus center, were observed to decompose thermally in the presence of 1,1‐dichloroethylene to produce [H3CPR3][Cl]. The major ruthenium‐containing product was a trichloro‐bridged ruthenium dimer that incorporates the elements of the 1,1‐dichloroethylene as a dichlorocarbene ligand and a styrenic vinyl group on the supporting NHC ligand. Spectroscopic, kinetic, and deuterium‐labeling experiments probed the mechanism of this process, which involves a rate‐limiting C–H activation of an NHC mesityl ortho methyl group. These studies provide insight into intrinsic decomposition processes of active Grubbs type olefin metathesis catalysts, pointing the way to new catalyst design directions.
Selective Benzylic and Allylic Alkylation of Protic Nucleophiles with Sulfonamides through Double Lewis Acid Catalyzed Cleavage of sp3 Carbon–Nitrogen Bonds
Authors: Liu Cong‐Rong , Li Man‐Bo , Yang Cui‐Feng , Tian Shi‐Kai 
Published: November 2008

AbstractThe acid‐catalyzed benzylic and allylic alkylation of protic nucleophiles is fundamentally important for the formation of carboncarbon and carbonheteroatom bonds, and it is a formidable challenge for benzylic and allylic amine derivatives to be used as the alkylating agents. Herein we report a highly efficient benzylic and allylic alkylation of protic carbon and sulfur nucleophiles with sulfonamides through double Lewis acid catalyzed cleavage of sp3 carbon–nitrogen bonds at room temperature. In the presence of a catalytic amount of inexpensive ZnCl2‐TMSCl (TMSCl: chlorotrimethylsilane), 1,3‐diketones, β‐keto esters, β‐keto amides, malononitrile, aromatic compounds, thiols, and thioacetic acid can couple with a broad range of tosyl‐activated benzylic and allylic amines to give diversely functionalized products in good to excellent yields and with high regioselectivity. Furthermore, the cross‐coupling reaction of 1,3‐dicarbonyl compounds with benzylic propargylic amine derivatives has been successfully applied to the one‐step synthesis of polysubstituted furans and benzofurans.
Size‐ and Distance‐Dependent Nanoparticle Surface‐Energy Transfer (NSET) Method for Selective Sensing of Hepatitis C Virus RNA
Authors: Griffin Jelani , Singh Anant Kumar , Senapati Dulal , Rhodes Patsy , Mitchell Kanieshia , Robinson Brianica , Yu Eugene , Ray Paresh Chandra 
Published: November 2008

AbstractWe report size‐ and distance‐dependent surface‐energy transfer (SET) properties of gold nanoparticles for recognizing hepatitis C virus (HCV) RNA sequence sensitively and selectively (single‐base mutations) in a homogeneous format. We have demonstrated that quenching efficiency increases by three orders of magnitude, as the particle size increases from 5 to 70 nm. Due to this extraordinarily high KSV, nanoparticle SET (NSET) detection limit can be as low as 300 fM concentration of RNA, depending on the size of gold nanoparticle. We have shown that the distance‐dependent quenching efficiency is highly dependent on the particle size and the distance at which the energy‐transfer efficiency is 50 %, ranges all the way from 8 nm, which is very close to the accessible distance of conventional Förster resonance energy transfer (FRET), to about 40 nm by choosing gold nanoparticles of different diameters. Our result points out that dipole‐to‐metal‐particle energy transfer and NSET models provide a better description of the distance dependence of the quenching efficiencies for 8 nm gold nanoparticle, but agreement is poor for 40 and 70 nm gold nanoparticles, for which the measured values were always larger than the predicted ones.
Synthesis and Structure of Heterodinuclear Rhodium and Iridium Borylene Complexes
Authors: Braunschweig Holger , Forster Melanie , Seeler Fabian 
Published: November 2008

AbstractHerein we report on the synthesis and structural characterization of a representative range of novel heterodinuclear bridging rhodium and iridium borylene complexes. The iridium borylene complexes feature an unusual coordination mode of the borylene ligand. Furthermore, the first instance of a heterodinuclear‐bridged borylene compound containing a chromium atom in the three‐membered ring is reported.
Direct Electrodeposition of Porous Gold Nanowire Arrays for Biosensing Applications
Authors: Zhang Xinyi , Li Dan , Bourgeois Laure , Wang Huanting , Webley Paul A. 
Published: November 2008

AbstractNanochannel alumina templates are used as templates for fabrication of porous gold nanowire arrays by a direct electrodeposition method. After modification with glucose oxidase, a porous gold nanowire‐array electrode is shown to be an excellent electrochemical biosensor for the detection of glucose. The picture shows an SEM image of a nanowire array after removal of the alumina template by acid dissolution.magnified imageWe report the fabrication of porous gold nanowire arrays by means of a one‐step electrodeposition method utilizing nanochannel alumina templates. The microstructure of gold nanowires depends strongly on the current density. The formation of porous gold nanowires is attributed to disperse crystallization under conditions of low nucleation rate. Interfacial electron transport through the porous gold nanowires is studied by electrochemical impedance spectroscopy. Cyclic voltammetric studies on the porous gold nanowire arrays reveal a low‐potential electrocatalytic response towards hydrogen peroxide. The properties of the glucose oxidase modified porous gold nanowire array electrode are elucidated and compared with those of nonporous enzyme electrodes. The glucose oxidase modified porous gold nanowire‐array electrode is shown to be an excellent electrochemical biosensor for the detection of glucose.