bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a stable isotope dilution UPLC‐MS/MS method for quantification of dexmedetomidine in a small amount of human plasma
Authors: Inoue Koichi , Sakamoto Tasuku , Fujita Yoshihito , Yoshizawa Saya , Tomita Maiko , Min Jun Zhe , Todoroki Kenichiro , Sobue Kazuya , Toyo'oka Toshimasa 
Published: February 2013

ABSTRACTDexmedetomidine (Dex) is a selective central α2‐agonist with anesthetic properties and has been used in clinical practice for sedation in the intensive care unit (ICU) after operations. In this study, an analytical assay for the determination of Dex in a small amount of plasma was developed for the application to pediatric ICU trials. The quantification of Dex was constructed using the original stable isotope Dex‐d3 for electrospray ionization‐tandem mass spectrometry (ESI‐MS/MS) in the selected reaction monitoring mode. A rapid ultra‐performance liquid chromatography technique was adopted using ESI‐MS/MS with a runtime of 3 min. Efficacious concentration levels (50 pg/mL to 5 ng/mL) could be evaluated using a very small amount of plasma (10 μL) from patients. The lower limit of the quantification was 5 pg/mL in the plasma (100 µL). For sample preparation, a solid‐phase extraction was used along with the OASIS‐HLB cartridge type. Recovery values ranged from 98.8 to 100.3% for the intra‐ [relative standard deviation (RSD), 0.9–1.3%] and inter‐ (RSD, 0.9–1.5%) day assays. A stable test had recovery values that ranged from 97.8 to 99.7% with an RSD of 1.0–1.9% for the process/wet extract, bench‐top, freeze–thaw and long‐term tests. This method was used to measure the Dex levels in plasma from pediatric ICU patients. In the clinical ICU trial, the small amount of blood (approximate plasma volume, 200 μL) remaining from blood gas analysis was reused and targeted for the clinical analysis of Dex in plasma. Copyright © 2013 John Wiley & Sons, Ltd.
Binary Compounds of Boron and Beryllium: A Rich Structural Arena with Space for Predictions
Authors: Hermann Andreas , Ashcroft N. W. , Hoffmann Roald 
Published: February 2013

AbstractWe explore ground‐state structures and stoichiometries of the BeB system in the static limit, with Be atom concentrations of 20 % or greater, and from P=1 atm up to 320 GPa. At P=1 atm, predictions are offered for several known compounds, the structures of which have not yet been determined experimentally. Specifically, at 1 atm, we predict a structure of R$\bar 3$m symmetry for the compound Be2B3, seen experimentally at high temperatures, which contains interesting BeBBBBe rods; and for the compound BeB4 we calculate metastability with respect to the elements with a structure similar to MgB4, which is quickly replaced as the pressure is elevated by a Cmcm structure that features 6‐ and 4‐membered rings in B cages, with Be interstitials. For another high‐temperature compound, Be2B, we confirm the CaF2 structure, but find a competitive and actually slightly more stable ground‐state structure of C2/m symmetry that features B2 pairs. In the case of BeB2, a material for which the stoichiometry has been the subject of debate, we have a clear prediction of a stable F$\bar 4$3m structure at P=1 atm. It has a diamondoid structure that is based on cubic (lower P) or hexagonal (higher P) diamond networks of B, but with Be in the interstices. This Zintl structure is a semiconductor at low and intermediate pressures. At higher pressures, BeB2 dominates the phase diagram. In general, the Zintl–Klemm concept of effective electron transfer from the more electropositive ion and bond formation among the resulting anions has proven useful in analyzing the structural preferences of many compositions in the BeB system at P=1 atm and at elevated pressures. An unusual feature of this binary system is that the 1:1 BeB stoichiometry never appears to reach stability in the static limit, although it comes close, as does Be17B12. Also stable at high pressures are stoichiometries BeB3, BeB4, and Be5B2.
Synthesis, Bonding and Reactivity of a Terminal Titanium Alkylidene Hydrazido Compound
Authors: Tiong Pei Jen , Groom Laura R. , Clot Eric , Mountford Philip 
Published: February 2013

AbstractWe report a detailed study of the reactions of the TiNNCPh2 alkylidene hydrazide functional group in [Cp*Ti{MeC(NiPr)2}(NNCPh2)] (8) with a variety of unsaturated and saturated substrates. Compound 8 was prepared from [Cp*Ti{MeC(NiPr)2}(NtBu)] and Ph2CNNH2. DFT calculations were used to determine the nature of the bonding for the TiNNCPh2 moiety in 8 and in the previously reported [Cp2Ti(NNCPh2)(PMe3)]. Reaction of 8 with CO2 gave dimeric [(Cp*Ti{MeC(NiPr)2}{μ‐OC(NNCPh2)O})2] and the “double‐insertion” dicarboxylate species [Cp*Ti‐{MeC(NiPr)2}{OC(O)N(NCPh2)C(O)O}] through an initial [2+2] cycloaddition product [Cp*Ti{MeC(NiPr)2}{N(NCPh2)C(O)O}], the congener of which could be isolated in the corresponding reaction with CS2. The reaction with isocyanates or isothiocyanates tBuNCO or ArNCE (Ar=Tol or 2,6‐C6H3iPr2; E=O, S) gave either complete NNCPh2 transfer, [2+2] cycloaddition to TiNα or single‐ or double‐substrate insertion into the TiNα bond. The treatment of 8 with isonitriles RNC (R=tBu or Xyl) formed σ‐adducts [Cp*Ti{MeC(NiPr)2}(NNCPh2)(CNR)]. With ArF5CCH (ArF5=C6F5) the [2+2] cycloaddition product [Cp*Ti{MeC(NiPr)2}{N(NCPh2)C(ArF5)C(H)}] was formed, whereas with benzonitriles ArCN (Ar=Ph or ArF5) two equivalents of substrate were coupled in a head‐to‐tail manner across the TiNα bond to form [Cp*Ti{MeC(NiPr)2}{N(NCPh2)C(Ar)NC(Ar)N}]. Treatment of 8 with RSiH3 (R=aryl or Bu) or Ph2SiH2 gave [Cp*Ti{MeC(NiPr)2}{N(SiHRR′)N(CHPh2)}] (R′=H or Ph) through net 1,3‐addition of SiH to the NNCPh2 linkage of 8, whereas reaction with PhSiH2X (X=Cl, Br) led to the TiNα 1,2‐addition products [Cp*Ti{MeC(NiPr)2}(X){N(NCPh2)SiH2Ph}].
Magnetic Anisotropy of the CC Single Bond
Authors: Baranac‐Stojanović Marija , Stojanović Milovan 
Published: February 2013

AbstractAnisotropic effects are broadly used in NMR spectroscopy for structure elucidation. With the development of computational methods it has become possible to quantify the effects and obtain further insight into their origin. Some classical interpretations have been questioned. Herein, we show that the classical “anisotropy cone” representing the anisotropic effect of the CC single bond should be revised: deshielding at its side and shielding along its end are observed. Consequently, methyl, methylene, and methyne hydrogen atoms are not deshielded by CC bonds as is conventionally explained in NMR spectroscopy textbooks. They are just less shielded than by the CH bonds attached at the same carbon. In addition, this anisotropic effect is dependent on the environment and care should be taken when drawing conclusions based on it. For example, it differs for the staggered and eclipsed conformations of ethane in HCCH planes, as well as for cyclohexane. In fact, it is not the anisotropy of the C2C3/C5C6 bonds that determines the chemical shift difference of axial and equatorial protons of a rigid cyclohexane ring, but magnetic contributions from all bonds.
Synthesis of gem‐Diaurated Species from Alkynols
Authors: Zhdanko Alexander , Maier Martin E. 
Published: February 2013

AbstractA number of enol ether‐derived diaurated species were synthesized directly from different alkynols and cationic gold complexes in the presence of a non‐nucleophilic base (proton sponge). The reaction can be easily applied for in situ generation of diaurated species from all common types of hydroalkoxylation substrates: 5‐endo, 5‐exo/6‐endo, 6‐exo/7‐endo and intermolecular types. Six examples were also synthesized in individual state as stable hexafluoroantimonate salts. Whereas diaurated species are obtained reliably from all conventional mononuclear gold catalysts, application of binuclear ones often gave diaurated species with unusual properties. The preliminary results point to complexities of behavior of binuclear gold catalysts and would require more research in future for this subclass. The formation of diaurated species from various gold‐oxo compounds (LAu)2OH+, (LAu)3O+, and LAuOH (L=phosphine ligand) was also studied. Of these three types, only (LAu)2OH+ is reactive, whereas (LAu)3O+ and LAuOH are not reactive alone but require acidic promoters to enable the reaction. These differences in reactivity were explained by ability of these compounds to generate the necessary acetylene π‐complex intermediate.
Self‐Assembly of Anionic Porphyrins and Alkaline or Alkaline Earth Metal Ions Mediated by Cucurbit[7,8]uril
Authors: Lei Wanhua , Jiang Guoyu , Zhou Qianxiong , Hou Yuanjun , Zhang Baowen , Cheng Xuexin , Wang Xuesong 
Published: February 2013

AbstractNanoscaled coordination polymers based on biologically prevalent ions have potential applications in drug delivery and biomedical imaging. Herein, coordination polymer nanoparticles of anionic porphyrins, including meso‐tetra(4‐carboxyphenyl)‐porphyrin (H2TCPP4−) and meso‐tetra(4‐sulfonatophenyl)‐porphyrin (H2TPPS4−), and alkaline or alkaline earth metal cations, such as K+ and Ca2+, were constructed in aqueous solution in the presence of cucurbit[7]uril (CB7) or cucurbit[8]uril (CB8). UV/Vis absorption and fluorescence spectroscopy, dynamic light scattering (DLS), scanning electron spectroscopy (SEM), and atomic force microscopy (AFM) were applied to explore the assembly and particle formation of porphyrin anions and metal cations mediated by CBn. The particle size depends on the kinds of CBn and metal cations and their concentrations. The uptake of H2TPPS4− particles by tumor cells (A549 cells) was found to be more efficient than H2TPPS4− at 37 °C, showing the application potential of such assembled particles in biology and medicine.
Anti‐Oligomannose Antibodies as Potential Serum Biomarkers of Aggressive Prostate Cancer
Authors: Wang Denong , Dafik Laila , Nolley Rosalie , Huang Wei , Wolfinger Russell D. , Wang Lai‐Xi , Peehl Donna M. 
Published: February 2013

Abstract

Preclinical Research

This study bridges a carbohydrate microarray discovery and a large‐scale serological validation of anti‐oligomannose antibodies as novel serum biomarkers of aggressive prostate cancer (PCa). Experimentally, a Man9‐cluster‐specific enzyme‐linked immunosorbent assay was established to enable sensitive detection of anti‐Man9 antibodies in human sera. A large‐cohort of men with PCa or benign prostatic hyperplasia (BPH) whose sera were banked at Stanford University was characterized using this assay. Subjects included patients with 100% Gleason grade 3 cancer (n = 84), with Gleason grades 4 and/or 5 cancer (n = 204), and BPH controls (n = 135). Radical prostatectomy Gleason grades and biochemical (PSA) recurrence served as key parameters for serum biomarker evaluation. It was found that IgGMan9 and IgMMan9 were widely present in the sera of men with BPH, as well as those with cancer. However, these antibody reactivities were significantly increased in the subjects with the largest volumes of high grade cancer. Detection of serum IgGMan9 and IgMMan9 significantly predicted the clinical outcome of PCa post‐radical prostatectomy. Given these results, we suggest that IgGMan9 and IgMMan9 are novel serum biomarkers for monitoring aggressive progression of PCa. The potential of oligomannosyl antigens as targets for PCa subtyping and targeted immunotherapy is yet to be explored.
Rational Synthesis and Mutual Conversion of Bis‐N‐heterocyclic Diphosphanes and Secondary N‐Heterocyclic Phosphanes
Authors: Puntigam Oliver , Förster Daniela , Giffin Nick A. , Burck Sebastian , Bender Johannes , Ehret Fabian , Hendsbee Arthur D. , Nieger Martin , Masuda Jason D. , Gudat Dietrich 
Published: February 2013

AbstractSymmetrical N‐heterocyclic 1,1′,3,3′‐tetrahydro‐2,2′‐bi‐1,3,2‐diazaphospholes and 2,2′‐bi‐1,3,2‐diazaphospholidines are prepared by time‐saving, sequential “one‐pot” syntheses starting from 1,4‐diazabutadienes or N‐alkyl or N‐aryl‐substituted ethane‐1,2‐diamines. This method offers high selectivity and minimizes the loss of products owing to unwanted hydrolysis, and thus grants high product yields. In some cases, secondary phosphanes were formed together with or instead of diphosphanes. This reaction is explained by a follow‐up process involving homolytic fission of diphosphanes to give phosphanyl radicals, which then react with ammonium salts to give a mixture of secondary phosphanes and chlorophosphanes. Even if its synthetic scope is as yet limited, this approach seems promising in offering superior selectivity and higher yields than common synthetic protocols that rely on the use of complex hydrides as reducing agents. In addition to the reductive conversion of diphosphanes into secondary phosphanes, a reverse reaction under exposure of the reactants to light is also reported.
A Divergent and Stereoselective Approach for the Syntheses of Some Polyhydroxylated Indolizidine and Pyrrolizidine Iminosugars
Authors: Rajender Anugula , Rao Jalagam Prasada , Rao Batchu Venkateswara 
Published: February 2013

AbstractA common, divergent, and efficient approach to the syntheses of (+)‐steviamine (9), (–)‐1‐deoxy‐8a‐epi‐castanospermine (10), (+)‐trihydroxyindolizidine (11), (+)‐3,7a‐di‐epi‐hyacinthacine A1 (12), and (–)‐2‐epi‐lentiginosine (4) was achieved by starting from D‐ribose‐derived intermediate 13. The key steps involved in these syntheses are a highly diasteroselective Grignard addition to a ribosylimine, a one‐pot stereoselective intramolecular reductive amination, a selectve deprotection of a silyl ether, and a ring‐closing metathesis (RCM) reaction.
Enantioselective Friedel–Crafts Alkylation of Indoles with (E)‐1‐Aryl‐4‐benzyloxybut‐2‐en‐1‐ones Catalyzed by an (R)‐3,3′‐Br2BINOLate–Hafnium(IV) Complex
Authors: Blay Gonzalo , Fernández Isabel , Muñoz M. Carmen , Pedro José R. , Vila Carlos 
Published: February 2013

AbstractA highly enantioselective Friedel–Crafts reaction of unprotected indoles with (E)‐1‐aryl‐4‐benzyloxybut‐2‐en‐1‐ones catalyzed by a new chiral [Hf{(R)‐3,3′‐Br2‐BINOL}(OtBu)2]2 complex has been developed to functionalize the C‐3 position of the indole nucleus with a side chain bearing a 1,4‐difunctionalized moiety and a benzylic stereogenic center. The reaction proceeds in good to excellent yields and excellent enantioselectivities (up to 97 % ee). The usefulness of this approach was illustrated with the synthesis of a tryptophol derivative.
ENVIRONMENTAL FATE OF THREE NOVEL BROMINATED FLAME RETARDANTS IN AQUATIC MESOCOSMS
Authors: de Jourdan Benjamin P. , Hanson Mark L. , Muir Derek C.G. , Solomon Keith R. 
Published: February 2013

Abstract

Currently, little is known about the environmental fate and persistence of novel brominated flame retardants (NBFRs). The recent detection of NBFRs in sediment cores and air samples provides insight into their persistence and potential for transport. Limited numbers of laboratory studies have examined the fate and behavior of these compounds, but field-based fate studies have been especially lacking. The authors conducted an aquatic mesocosm experiment to assess the behavior of three NBFRs: bis(tribromophenoxy)ethane (BTBPE), tetrabromobisphenol A bis(2,3-dibromopropyl ether; TBBPA-DBPE), and Firemaster BZ-54, a commercial mixture containing bis(2-ethylhexyl)tetrabromophthalate (BEHTBP) and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTeBB) in a ratio of 1:4. Analysis by gas chromatography–mass spectrometry, operated in the electron capture negative ionization mode, revealed partitioning between the particulate and sediment phases, with BTBPE, TBBPA-DBPE, and BEHTBP identified as being environmentally persistent in both the particulate and the sediment compartments. The median dissipation times (DT50) differed in each compartment, with more rapid disappearance in the particulate (9–30 d) compared with the sediment compartment (&gt;100 d) for each compound. The degradation products were more concentrated in the particulate compartment and corresponded to known photodegradation products. The ratio of EHTeBB to BEHTBP differed in the mesocosm compartments compared with the technical product used for treatment, indicating increased degradation of EHTeBB relative to BETHBP. Environ. Toxicol. Chem. 2013;32:1060–1068. © 2013 SETAC
Acute exposure to DE-71 causes alterations in visual behavior in zebrafish larvae
Authors: Chen Lianguo , Huang Yubin , Huang Changjiang , Hu Bing , Hu Chenyan , Zhou Bingsheng 
Published: February 2013

Abstract

Polybrominated diphenyl ethers (PBDEs) cause neurobehavioral toxicity, but their effects on visual behavior remain unknown. In the present study, the impact of PBDEs on visual behavior was examined using optokinetic responses and phototaxis in zebrafish larvae. Zebrafish embryos were exposed to pentabrominated diphenyl ethers mixture (DE-71) at concentrations of 0, 0.32, 3.58, and 31.0 µg/L until 15 d postfertilization. The authors then assessed photoreceptor opsin expression, retinal histology, and visual behavior of the larvae. The results showed that the transcriptions of the opsin genes, zfrho and zfgr1, were significantly upregulated. Western blotting further demonstrated a significant increase in rhodopsin protein expression after exposure of the larvae to DE-71. Histological examination revealed the following morphological alterations in the retina: increased area of inner nuclear layer, decreased area of inner plexiform layer, and decreased density of ganglion cells. Tests of optokinetic and phototactic behavior showed hyperactive responses on exposure to DE-71, including increased saccadic eye movements and phototactic response. The present study is the first to demonstrate that the acute exposure of zebrafish larvae to DE-71 causes biochemical and structural changes in the eye that lead to behavioral alterations. Analysis of these visual behavioral paradigms may be useful in predicting the adverse effects of toxicants on visual function in fish. Environ Toxicol Chem 2013;32:1370–1375. © 2013 SETAC
BIOACCUMULATION AND BIOMAGNIFICATION OF MERCURY AND SELENIUM IN THE SARASOTA BAY ECOSYSTEM
Authors: Hong Yong-Seok , Hull Peter , Rifkin Erik , Bouwer Edward J. 
Published: February 2013

Abstract

The bioaccumulation and biomagnification of Hg and Se were investigated in Sarasota Bay, Florida, USA, to characterize the Hg exposure risks to wild bottlenose dolphins in the bay. Concentrations of total mercury (THg), monomethylmercury (MMHg), and total selenium (TSe) were monitored in the bay, the latter of which might reduce Hg toxicity. The food web structure and dolphins' trophic level–specific consumption rates were evaluated using stable isotope ratios of carbon (δ13C) and nitrogen (δ15N). Regressions developed for Hg biomagnification in the food chain were log10CTHg (nanograms per gram) = 0.27 × δ15N (‰) – 0.42, R2 = 0.87, for THg and log10CMMHg = 0.33 × δ15N (‰) – 1.0, R2 = 0.93, for MMHg. Unlike Hg, nearly constant TSe concentrations were observed at 248 ± 179 ng g−1 in the food web, and the TSe-to-THg molar ratio was predicted by log10(CTSe/CTHg) = −0.10 × δ15N (‰) + 2.8, R2 = 0.60. The THg-uptake rates of Sarasota bottlenose dolphins are estimated to vary between 2.1 and 4.9 µg kg−1 d−1; however, the estimated TSe-uptake rates (15.1 µg kg−1 d−1) were higher than those for THg, and the Hg-exposure risks of the Sarasota Bay resident bottlenose dolphins are considered to be low. Approaches employed in the present study can be extended to other environments to characterize Hg contamination in aquatic systems and Hg exposure risks in top predators. Environ. Toxicol. Chem. 2013;32:1143–1152. © 2013 SETAC
Numerical diffusion for flow‐aligned unstructured grids with application to estuarine modeling
Authors: Holleman Rusty , Fringer Oliver , Stacey Mark 
Published: February 2013

SUMMARYThe benefits of unstructured grids in hydrodynamic models are well understood but in many cases lead to greater numerical diffusion compared with methods available on structured grids. The flexible nature of unstructured grids, however, allows for the orientation of the grid to align locally with the dominant flow direction and thus decrease numerical diffusion. We investigate the relationship between grid alignment and diffusive errors in the context of scalar transport in a triangular, unstructured, 3‐D hydrodynamic code. Analytical results are presented for the 2‐D anisotropic numerical diffusion tensor and verified against idealized simulations. Results from two physically realistic estuarine simulations, differing only in grid alignment, show significant changes in gradients of salinity. Changes in scalar gradients are reflective of reduced numerical diffusion interacting with the complex 3‐D structure of the transporting flow. We also describe a method for utilizing flow fields from an unaligned grid to generate a flow‐aligned grid with minimal supervision. Copyright © 2013 John Wiley & Sons, Ltd.
Detecting unfrozen sediments below thermokarst lakes with surface nuclear magnetic resonance
Authors: Parsekian Andrew D. , Grosse Guido , Walbrecker Jan O. , Müller‐Petke Mike , Keating Kristina , Liu Lin , Jones Benjamin M. , Knight Rosemary 
Published: February 2013

AbstractA talik is a layer or body of unfrozen ground that occurs in permafrost due to an anomaly in thermal, hydrological, or hydrochemical conditions. Information about talik geometry is important for understanding regional surface water and groundwater interactions as well as sublacustrine methane production in thermokarst lakes. Due to the direct measurement of unfrozen water content, surface nuclear magnetic resonance (NMR) is a promising geophysical method for noninvasively estimating talik dimensions. We made surface NMR measurements on thermokarst lakes and terrestrial permafrost near Fairbanks, Alaska, and confirmed our results using limited direct measurements. At an 8 m deep lake, we observed thaw bulb at least 22 m below the surface; at a 1.4 m deep lake, we detected a talik extending between 5 and 6 m below the surface. Our study demonstrates the value that surface NMR may have in the cryosphere for studies of thermokarst lake hydrology and their related role in the carbon cycle.
MicroRNA-140-5p suppresses tumor growth and metastasis by targeting transforming growth factor β receptor 1 and fibroblast growth factor 9 in hepatocellular carcinoma
Authors: Yang Hao , Fang Feng , Chang Ruimin , Yang Lianyue 
Published: February 2013

Abstract

By comparing the expression profiles of microRNAs (miRNAs) in different hepatocellular carcinoma (HCC) subtypes, we identified miR-140-5p as an HCC-related miRNA. We found that miR-140-5p was significantly decreased in HCC tissues and all of six liver cancer cell lines examined and its expression levels were correlated with multiple nodules, vein invasion, capsular formation, and differentiation, as well as overall and disease-free survival of HCC. We also found that miR-140-5p suppressed HCC cell proliferation and HCC metastasis. Multipathway reporter arrays suggested that miR-140-5p inhibited transforming growth factor β (TGF-β) and mitogen-activated protein kinase / extracellular signal-regulated kinase (MAPK/ERK) signaling. TGFB receptor 1 (TGFBR1) and fibroblast growth factor 9 (FGF9) were then characterized as the direct targets for miR-140-5p after it was found that ectopic miR-140-5p expression suppressed TGFBR1 and FGF9 expression. Silencing TGFBR1 and FGF9 by small interfering RNA (siRNA) resembled the phenotype resulting from ectopic miR-140-5p expression, while overexpression of TGFBR1 and FGF9 attenuated the effect of miR-140-5p on HCC growth and metastasis. Conclusion: These data elucidated a tumor suppressor role for miR-140-5p in HCC development and progression with therapeutic potential. Our correlation studies in clinical HCC samples further suggest that miR-140-5p could be a valuable biomarker for HCC prognosis. (Hepatology 2013 )