bluuebunny/crossref_metadata_2025_split huggingface dataset:
Splanchnic Spillover of Extracellular Lipase–Generated Fatty Acids in Overweight and Obese Humans
Authors: Nelson Robert H. , Basu Rita , Johnson C. Michael , Rizza Robert A. , Miles John M. 
Published: September 2007

OBJECTIVE—Triglyceride-rich lipoproteins, primarily chylomicrons, can contribute to plasma free fatty acid (FFA) concentrations via spillover of fatty acids during intravascular hydrolysis into the venous effluent of some tissues. The present study was undertaken to determine whether spillover occurs in the splanchnic bed of humans.
RESEARCH DESIGN AND METHODS—Arterial and hepatic venous blood was sampled in postabsorptive (n = 6; study A) and postprandial (n = 5; study B) obese humans during infusion of carbon-labeled (14C or 13C) oleate and 3H triolein, the latter incorporated into a lipid emulsion as a surrogate for chylomicrons. Spillover was determined by measuring production of 3H oleate.
RESULTS—Splanchnic spillover was higher than nonsplanchnic systemic spillover in both study A (60 ± 7 vs. 24 ± 6%; P &lt; 0.01) and study B (54 ± 3 vs. 16 ± 5%; P &lt; 0.005). Because portal vein sampling is not feasible in humans, assumptions regarding actual spillover in nonhepatic splanchnic tissues were required for the spillover calculation. A mathematical model was developed and demonstrated that nonhepatic splanchnic spillover rates in study A and study B of 69 and 80%, respectively, provided the best fit with the data. There was preferential splanchnic uptake of triglyceride fatty acids compared with FFAs in study B (fractional extraction 61 ± 3 vs. 33 ± 2%; P &lt; 0.005).
CONCLUSIONS—These data confirm previous studies indicating that the transport of FFAs and triglyceride fatty acids are partitioned in tissues and indicate that splanchnic spillover from triglyceride-rich lipoproteins may be a significant source of both portal venous and systemic FFAs.
Peroxynitrite: In vivo and In vitro synthesis and oxidant degradative action on biological systems regarding biomolecular injury and inflammatory processes
Authors: Hrabárová E. , Gemeiner P. , Šoltés L. 
Published: September 2007

AbstractThis review summarizes all significant data regarding peroxynitrite chemistry, the ways of its synthetic preparation as well as the degradative action of this species on biomolecules, in particular glycosaminoglycans, among which the hyaluronan degradation by peroxynitrite has recently been the subject of greater interest than ever before. The complex chemical behavior of a peroxynitrite molecule is strongly influenced by a few factors; conformational structural forms, active intermediates release, presence of CO2 and trace transition metals, different reaction conditions, as well as the rules of kinetics. Special attention was focused on monitoring of the kinetics of the degradative action of peroxynitrite in or without the presence of residual hydrogen peroxide on high-molar-mass hyaluronan.
Coupling of microwave induced plasma optical emission spectrometry with HPLC separation for speciation analysis of Cr(III)/Cr(VI)
Authors: Heltai G. , Fehér B. , Horváth M. 
Published: September 2007

AbstractFeasibility and limitations of direct coupling of high performance liquid chromatographic (HPLC) separation to microwave induced plasma (MIP)-optical emission spectrometry (OES) for elementspecific detection was tested and compared to inductively coupled plasma (ICP)-optical emission spectrometric detection on the basis of the Cr(III)/Cr(VI) speciation analysis of water samples. Coupling was performed by a hydraulic high pressure nebulizer (HHPN) radiative-heating/watercooling interface which provides about 20 % and 80 % aerosol yield in the case of helium and argon carrier gases, respectively. Desolvation efficiency of aqueous solutions was approximately 80 %. Applying the ion-pair HPLC separation, the organic eluents and reagents in the MIP cause a 50–75 % signal suppression for Cr(VI) and 25–50 % for Cr(III). In a pure aqueous solution the MIP Cr(VI) signal was by 20 % lower than that of Cr(III). These effects were lower using the ICP source, but they cannot be neglected. Easily ionizable matrix elements (Na, Ca) can cause 70 % signal suppression in the MIP, and 20 % in the ICP. Therefore, species dependent calibration is required in both cases. In the case of HPLC detection by MIP-OES, the detection limit was 13 ng for Cr(III), and 18 ng for Cr(VI). Using the ICP-OES detection, the detection limit was 0.2 ng for Cr (III) and 0.4 ng for Cr (VI). The linear dynamic ranges in both cases were two orders of magnitude.
Determination of nitrites by the formation of bisazo dye
Authors: Dayananda B. , Revanasiddappa H. 
Published: September 2007

AbstractA facile, sensitive and rapid spectrophotometric method for the determination of nitrite is presented. The method involves the reaction of nitrite with 4-aminoazobenzene under acidic conditions in the presence of a bromide ion allowing to complete the diazotization reaction almost instantaneously. The formed diazonium ion is then coupled with acetyl acetone to give bisazo dye in an aqueous alkaline medium having maximum absorption at 500 nm. The molar absorptivity and Sandell’s sensitivity of the method were found to be 4.2 × 104 dm3 mol−1 cm−1 and 1.1 ng cm−2, respectively. The system obeys the Beer’s law within the concentration range of 0.1–9 µg of nitrite in the final sample volume of 10 cm3. Optimum reaction conditions were evaluated and the influence of ionic interference on the determination of nitrite has been studied. The developed method has been applied in the determination of nitrite in water and soil samples, and the results were statistically evaluated.
Determination of As(III) and total as in water by graphite furnace atomic absorption spectrometry after electrochemical preconcentration on a gold-plated porous glassy carbon electrode
Authors: Střelec M. , Čacho F. , Manová A. , Beinrohr E. 
Published: September 2007

AbstractArsenic(III) was preconcentrated in a flow-through electrochemical cell on a gold coated porous carbon electrode. On stripping, arsenic was eluted with diluted nitric acid and determined off-line by GF AAS. The deposition and stripping steps were optimized. The limit of detection and limit of quantification were found to be 1.9 µg L−1 and 6.4 µg L−1, respectively. The repeatability and reproducibility were found to be 5.3 % and 9.3 %, respectively. Total arsenic was determined after a microwave assisted chemical reduction of As(V) to As(III) making the procedure suitable for speciation analysis. The method was applied in analysis of water samples.
Chromaticity of poly(o-toluidine) matrix enhanced by anion-exchange mechanism
Authors: Ahmed S. 
Published: September 2007

AbstractThe incorporation of 9,10-anthraquinone-1,5-disulfonate (AQS2) into the protonated form of poly(o-toluidine) (POT), produced by oxidative polymerization of the cationic form of the monomer or by doping the basic form (POT-EB) by anion-exchange has been studied by FTIR and UV-VIS spectroscopy and mass spectrometry. The presence of sulfur and the absence of chlorine proven by elemental analysis of the polymer product confirmed the substitution of the chloride anion with AQS2 in the matrix. Molecular mechanics (MM+) calculations suggest that the optimal geometric structure (OMG) of AQS2-doped POT is at least three (3.92) times more stable than that of the parent chloride-doped POT (HCl-doped POT). The increase of the absorbance at about 840 nm associated with the increasing concentration of AQS2 revealed the insertion of AQS2 into the POT chain. This observation could be explained by the diffusion of AQS2 in the polymer chain. Kinetic parameters of the oxidative polymerization of the cationic form of o-toluidine (o-T-HClO4) in the presence of different amounts of AQS2 were deduced on the basis of absorbance variations. The results of computer-oriented kinetic analysis indicate that the rate-controlling step of the o-T polymerization is governed by the Ginstling-Bronstein equation representing the three-dimensional diffusion (D4). Activation parameters of the oxidative polymerization of protonated o-T in the presence of varying amount of AQS2 were computed and discussed.
Ethanol/water pulp enzymatic pretreatment: Chemical and FTIR-PCA analyses
Authors: Ruzene D. , Gonçalves A. 
Published: September 2007

AbstractPulps obtained from ethanol/water cooking of sugarcane bagasse were treated at different times using xylanase enzyme obtained from Thermomyces lanuginosus IOC-4145 or commercially (Cartazyme HS, Sandoz Products Ltd.). The enzyme dosage was 18 IU per g of dry pulp and the time varied from 4 h to 12 h. When xylanase from T. lanuginosus was used, the kappa number and viscosity improved independently of the processing time used (4 h, 8 h, and 12 h). After chemical evaluation, the obtained pulps were classified using Fourier Transformed Infra-Red Spectroscopy and Principal Component Analysis. The results showed that the first three principal components explained more than 90 % of the total variance of the pulp spectra.
Spectroscopic and thermodynamic studies of complexation of some divalent metal ions with isatin-β-thiosemicarbazone
Authors: Konstantinović S. , Radovanović B. , Todorović Z. , Ilić S. , Konstantinović B. 
Published: September 2007

AbstractMetal complexes of some divalent metal ions (Co, Ni, Cu, Zn, Hg, and Pd) with isatin-β-thiosemicarbazone (ITS) as the Schiff base have been investigated potentiometrically and spectrophotometrically. The dissociation constants of the ligand and formation constants of the metal complexes, as well as the corresponding thermodynamic functions (ΔG, ΔH and ΔS) have been determined at different temperatures in ethanol—water solution. The full stability constants were also evaluated spectrophotometrically by the Job method. The experimental results indicate that Cu(II), Zn(II), Pd(II), and Hg(II) form one-to-one molecular complexes (ML) with the studied ligand, whereas Co(II) and Ni(II) form both ML and ML2 species.
Structural and spectroscopic analysis of dipeptide l-methionyl-glycine and its hydrochloride
Authors: Koleva B. , Kolev T. , Todorov S. 
Published: September 2007

AbstractDipeptide l-methionyl-glycine (Met-Gly) hydrochloride was characterized structurally by means of solid-state linear polarized IR (IR-LD) spectroscopy of oriented samples as colloidal suspension in nematic liquid crystal. Quantum chemical ab initio calculations and vibrational analysis support the experimental data. 1H and 13C nuclear magnetic resonance (NMR) data, mass spectrometry (ESI-MS and FAB-MS) techniques, thermogravimetry (TGV), and differential scanning calorimetry (DSC) method were employed as well. The experimental and theoretical data of hydrochloride salt were compared with analogous data of the neutral dipeptide with the aim to explain the role of intermolecular hydrogen bonding on the conformational behavior and spectroscopic properties of the compound studied.
Design and synthesis of paclitaxel conjugated with an ErbB2‐recognizing peptide, EC‐1
Authors: Li Peng , Jiang Sheng , Pero Stephanie C. , Oligino Lyn , Krag David N. , Michejda Christopher J. , Roller Peter P. 
Published: September 2007

AbstractThe selective delivery of therapeutic agents to receptors overexpressed in cancer cells without harming the rest of the body is a major challenge in clinical oncology today. In this study, we report the design and synthesis of paclitaxel (PTX) conjugated with an erbB2‐recognizing peptide (EC‐1). The cyclic peptide EC‐1 specifically binds to the extracellular domain of ErbB2 and selectively inhibits proliferation of breast cancer cells overexpressing ErbB2. PTX is a potent antitumor agent commonly used in the treatment of advanced metastatic breast cancer, yet patients have to suffer some side effects caused by its systemic toxicity. The aim of our conjugate is to specifically deliver antitumor agent PTX to breast cancer cells that overexpress oncogenic ErbB2 with the purpose to reduce toxicity and enhance selective killing of cancer cells. In this study, a concise and efficient synthetic route for the preparation of the PTX‐EC‐1 conjugate has been developed in 6% overall yield. This synthetic approach provides a general method for conjugating a highly functionalized and disulfide‐bridge containing cyclopeptide to Taxol or other antitumor agents. © 2007 Wiley Periodicals, Inc. Biopolymers 87: 225–230, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
The effect of changes in the bulk dielectric constant on the DNA torsional properties
Authors: de Souza Fátima Pereira , Neto Augusto Agostinho , Fossey Marcelo Andrés , Neto João Ruggiero 
Published: September 2007

AbstractThe effect of changes in the bulk dielectric constant on the DNA torsional properties was evaluated from plasmid circularization reactions. In these reactions, pUC18 previously linearized by EcoRI digestion was recircularized with T4 DNA ligase. The bulk dielectric constant of the reaction medium was decreased by the addition of different concentrations of neutral solutes: ethylene glycol, glycerol, sorbitol, and sucrose, or increased by the addition of glycine. The topoisomers generated by the ligase reaction were resolved by agarose‐gel electrophoresis. The DNA twist energy parameter (κ), which is an apparent torsional constant, was determined by linearization of the Gaussian topoisomers' distribution. It was observed that the twist energy parameter for the given solutes is almost linearly dependent on the bulk dielectric constant. In the reaction buffer, the twist energy parameter was determined to be 1100 ± 100. By decreasing the dielectric constant to 74 with the addition of sorbitol, the value of the parameter reaches κ = 900 ± 100, whereas the addition of ethylene glycol leads to κ = 400 ± 50. Upon addition of glycine, which resulted in a dielectric constant equal to 91, the value of the twist energy parameter increased to κ = 1750 ± 100. © 2007 Wiley Periodicals, Inc. Biopolymers 87: 244–248, 2007.This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Control of the Deprotonation Route of an Aminium Cation by the Solvent Polarity
Authors: Goez Martin , Sartorius Ingo 
Published: September 2007

AbstractWe have studied the photoreaction of triethylamine DH with the triplet sensitizer 9,10‐anthraquinone in a series of aprotic solvents with relative permittivity· varying between 2 and 50. The results are compared with those of an earlier investigation in which a series of triplet sensitizers in acetonitrile was used. All these reactions are two‐step processes: an aminium cation DH is formed by photoinduced electron transfer, and then deprotonated at Cα to give an α‐aminoalkyl radical D′. The deprotonation of DH can either occur within the cage, by the sensitizer radical anion, or outside the cage, by surplus amine. The final reaction products (e.g. N,N‐diethylvinylamine) are independent of the deprotonation route. Nevertheless, a distinction between the two mechanistic alternatives is possible by using measurements of chemically induced dynamic nuclear polarization (CIDNP). This technique is sensitive to radical pairs only, and the different amine‐based intermediates contained in the two possible kinds of radical pairs (radical‐ion pairs for both deprotonation routes, and pairs of neutral radicals for in‐cage deprotonation only) give rise to characteristically different signal patterns. The influence of solvent polarity as well as sensitizer oxidation potential Eox on the deprotonation pathway (exclusive in‐cage deprotonation at low values of· or high Eox, and exclusive out‐of‐cage deprotonation at high· or low Eox) can be quantitatively explained by the dependence of the in‐cage deprotonation rate on the driving force ‐ΔGdep0 of this process, which shows a marked threshold behavior. If ΔGdep0 is more negative than ‐125 kJ/mol, proton transfer from DH to the sensitizer radical anion is faster than separation of the primarily formed radical‐ion pair, so the aminium cations are deprotonated within the cage. For ΔGdep0 more positive than ‐100 kJ/mol, this reaction is too slow to compete with escape from the cage. By the latter process, free aminium cations are formed, which are then deprotonated outside the cage by surplus amine.
A Stereoselective Synthesis of (E)‐α, β‐Unsaturated Ketones Involving the Reactions of Organocerium Reagents with Secondary β‐Enamino Ketones
Authors: Bartoli Giuseppe , Marcantoni Enrico , Petrini Marino , Sambri Letizia 
Published: September 2007

AbstractStereoselective construction of trisubstituted alkenes has wide applicability to the synthesis of many natural products Specifically, β‐disubstituted enones are important functionalized trisubstituted alkene targets. The reaction of organocerium reagents with secondary β‐enamino ketones affords β=disubsituted α,β‐unsaturated ketones in fairly good yields. This process shows considerable stereoselectivity, and α,β‐unsaturated ketones of (E) configuration are predominantly observed. Organolithium‐derived cerium reagents display better stereoselectivity than organomagnesium‐based ones. The mechanism of the reaction varies with nitrogen substitution: N‐phenyl groups give 1,2‐addition products, whereas substitution products are observed with N‐alkyl groups. When organocerium reagents were used with β‐enamino ketones bearing secondary alkyl groups at the nitrogen atom, a lack of reactivity was observed.
Comparison of body‐fitted, embedded and immersed solutions of low Reynolds‐number 3‐D incompressible flows
Authors: Löhner Rainald , Appanaboyina Sunil , Cebral Juan R. 
Published: September 2007

AbstractThe solutions obtained for low Reynolds‐number incompressible flows using the same flow solver and solution technique on body‐fitted, embedded surface and immersed body grids of similar size are compared. The cases considered are a sphere at Re = 100 and an idealized stented aneurysm. It is found that the solutions using all these techniques converge to the same grid‐independent solution. On coarser grids, the effect of higher‐order boundary conditions is noticeable. Therefore, if the manual labor required to set up a body‐fitted domain is excessive (as is often the case for patient‐specific geometries with medical devices), and/or computing resources are plentiful, the embedded surface and immersed body approaches become very attractive options. Copyright © 2007 John Wiley & Sons, Ltd.
Population differences in the International Multi‐Centre ADHD Gene Project
Authors: Neale Benjamin M. , Sham Pak C. , Purcell Shaun , Banaschewski Tobias , Buitelaar Jan , Franke Barbara , Sonuga‐Barke Edmund , Ebstein Richard , Eisenberg Jacques , Mulligan Aisling , Gill Michael , Manor Iris , Miranda Ana , Mulas Fernando , Oades Robert D. , Roeyers Herbert , Rothenberger Aribert , Sergeant Joseph , Steinhausen Hans‐Christoph , Taylor Eric , Thompson Margaret , Zhou Kaixin , Asherson Philip , Faraone Stephen V. 
Published: September 2007

AbstractThe International Multi‐Centre ADHD Gene sample consists of 674 families from eight countries (Belgium, England, Germany, Holland, Ireland, Israel, Spain, and Switzerland) ascertained from clinics for combined‐type attention definity hyperactivity disorder in an offspring. 863 SNPs were successfully genotyped across 47 autosomal genes implicated in psychiatric disorders yielding a single nucleotide polymorphism (SNP) density of approximately one SNP per 2.5 kb. A global test of heterogeneity showed 269 SNPs nominally significant (expected 43). Inclusion of the Israeli population accounted for approximately 70% of these nominally significant tests. Hardy‐Weinberg equilibrium tests suggest that combining all these populations would induce stratification, but that the Northern European populations (Belgium, England, Germany, Holland, and Ireland) could be appropriate. Tag SNPs were generated using pair‐wise and aggressive tagging from Carlson et al. [2004] and de Bakker et al. [2005], respectively, in each population and applied to the other populations. Cross‐population performance across Northern Europe was consistent with within population comparisons. Smaller sample size for each population tended to yield more problems for the generation of aggressive tags and the application of pair‐wise tags. Any case‐control sample employing an Israeli sample with Northern Europeans must consider stratification. A Northern European tag set, however, appears to be appropriate for capturing the variation across populations. Genet. Epidemiol. 2008. © 2007 Wiley‐Liss, Inc.
Integration of signaling pathways regulating chondrocyte differentiation during endochondral bone formation
Authors: Adams Sherrill L. , Cohen Arthur J. , Lassová Luisa 
Published: September 2007

AbstractDuring endochondral bone formation, chondrocytes undergo a process of terminal differentiation or maturation, during which the rate of proliferation decreases, cells become hypertrophic, and the extracellular matrix is altered by production of a unique protein, collagen X, as well as proteins that promote mineralization. The matrix surrounding the hypertrophic chondrocytes eventually becomes mineralized, and the mineralized matrix serves as a template for bone deposition. This process is responsible for most longitudinal bone growth, both during embryonic development and in the postnatal long bone growth plates. Chondrocyte maturation must be precisely controlled, balancing proliferation with terminal differentiation; changes in the rate of either proliferation or differentiation result in shortened bones. Numerous signaling molecules have been implicated in regulation of this process. These include the negative regulators Indian hedgehog (Ihh) and parathyroid hormone‐related protein (PTHrP; Pthlh, PTH‐like hormone), as well as a number of positive regulators. This review will focus on several positive regulators which exert profound effects on chondrocyte maturation: the thyroid hormones T3 and T4, retinoic acid (the major active metabolite of vitamin A) and bone morphogenetic proteins (BMPs), as well as the transcription factor Runx2. Each of these molecules is essential for endochondral bone formation and cannot compensate for the others; abrogation of any one of them prevents differentiation. The important features of each of these signaling pathways will be discussed as they relate to chondrocyte maturation, and a model will be proposed suggesting how these pathways may converge to regulate this process. J. Cell. Physiol. 213:635–641. © 2007 Wiley‐Liss, Inc.