bluuebunny/crossref_metadata_2025_split huggingface dataset:
“Click‐to‐Chelate”: Design and Incorporation of Triazole‐Containing Metal‐Chelating Systems into Biomolecules of Diagnostic and Therapeutic Interest
Authors: Struthers Harriet , Spingler Bernhard , Mindt Thomas L. , Schibli Roger 
Published: May 2008

AbstractThe site‐specific conjugation of metal chelating systems to biologically relevant molecules is an important contemporary topic in bioinorganic and bioorganometallic chemistry. In this work, we have used the CuI‐catalyzed cycloaddition of azides and terminal alkynes to synthesise novel ligand systems, in which the 1,2,3‐triazole is an integral part of the metal chelating system. A diverse set of bidentate alkyne building blocks with different aliphatic and aromatic backbones and various donor groups were prepared. The bidentate alkynes were reacted with benzyl azide in the presence of a catalytic amount of CuI to form tridentate model ligands. The chelators were reacted with [ReBr3(CO)3]2− to form well‐defined and stable complexes with different overall charges, structures and hydrophilicities. In all cases tridentate coordination of the ligands, including through N3 of the 1,2,3‐triazole ring, was observed. The ligand systems could also be quantitatively radiolabelled with the precursor [99 mTc (H2O)3(CO)3]+ at low ligand concentrations. Similarly the alkynes were reacted with an azido thymidine derivative to form a series of compounds, which could be radiolabelled in situ to form single products. Subsequent incubation of the neutral and cationic organometallic 99 mTc thymidine derivatives with human cytosolic thymidine kinase, a key enzyme in tumour proliferation, revealed that only the neutral compounds maintained substrate activity towards the enzyme. Bioconjugation, radiolabelling and enzymatic reactions were successfully performed in a matter of hours. Thus, click chemistry provides an elegant method for rapidly functionalising a biologically relevant molecule with a variety of efficient metal chelators suitable for (radio)labelling with the M(CO)3 core (M=99 mTc, Re), to offer new potential for technetium‐99 m in clinical and preclinical tracer development.
Protonated Macrobicyclic Hosts Containing Pyridine Head Units for Anion Recognition
Authors: Esteban‐Gómez David , Platas‐Iglesias Carlos , de Blas Andrés , Fabbrizzi Luigi , Rodríguez‐Blas Teresa 
Published: May 2008

AbstractIn this paper, we report two macrobicyclic receptors containing pyridine head units derived from 1,10‐diaza‐15‐crown[5] (L1) or 4,13‐diaza‐18‐crown[6] (L2) that can be protonated in MeCN and used for anion recognition. The interaction of these protonated lateral macrobicycles with different anions has been investigated by means of spectrophotometric titrations in MeCN. The association constants for the complexes of halide anions with the protonated macrobicycles follow the sequences Cl−>Br−>I−>F− (L1) and Cl−>F−>I−>Br− (L2), whereby an increase of more than two logarithmic units is observed from F− to Cl− for the binding constants of the receptor derived from L1. The association constants also indicate an important degree of selectivity of these macrobicyclic receptors for Cl− over Br− or I−. The X‐ray crystal structure analyses of the chloride and bromide complexes confirms the formation of the envisaged supramolecular complexes. Moreover, the binding constants indicate that these receptors present a high sulfate‐to‐nitrate binding selectivity. The stability trend observed for the recognition of halide anions by the macrobicycles presented herein as well as the sulfate‐to‐nitrate binding selectivity have been rationalised by means of DFT calculations at the B3LYP/LanL2DZ level. These studies indicate that the especially high binding selectivity for Cl− is the result of the optimum fit between the protonated macrobicyclic cavity and the size of the anion, whereas the sulfate‐to‐nitrate selectivity results from shape complementarity between the hydrogen‐binding acceptor sites on sulfate and the hydrogen‐bond donors of the macrobicycle.
Conformationally Restricted Dipyrromethene Boron Difluoride (BODIPY) Dyes: Highly Fluorescent, Multicolored Probes for Cellular Imaging
Authors: Zheng Qingdong , Xu Gaixia , Prasad Paras N. 
Published: May 2008

AbstractNovel fluorescent, conformationally restricted dipyrromethene boron difluoride (BODIPY) dyes have been prepared by introducing a naphthalenyl group at the meso position of the BODIPY core. These BODIPY dyes exhibit increased fluorescence quantum yields compared with dyes that have a meso‐position phenyl group with internal rotation. The absorption and emission wavelengths of such conformationally restricted BODIPY dyes can be easily tuned to the near‐IR range by derivatization through a condensation reaction with benzaldehyde derivatives. The two‐photon absorption properties of these BODIPY dyes were also investigated and the results show that they exhibit increased two‐photon excited fluorescence compared to analogue dyes that contain a phenyl group. The one‐ and two‐photon fluorescence imaging of living cells by using selected BODIPY dyes has been successfully demonstrated.
Statistical mixture modeling for cell subtype identification in flow cytometry
Authors: Chan Cliburn , Feng Feng , Ottinger Janet , Foster David , West Mike , Kepler Thomas B. 
Published: May 2008

AbstractStatistical mixture modeling provides an opportunity for automated identification and resolution of cell subtypes in flow cytometric data. The configuration of cells as represented by multiple markers simultaneously can be modeled arbitrarily well as a mixture of Gaussian distributions in the dimension of the number of markers. Cellular subtypes may be related to one or multiple components of such mixtures, and fitted mixture models can be evaluated in the full set of markers as an alternative, or adjunct, to traditional subjective gating methods that rely on choosing one or two dimensions. Four color flow data from human blood cells labeled with FITC‐conjugated anti‐CD3, PE‐conjugated anti‐CD8, PE‐Cy5‐conjugated anti‐CD4, and APC‐conjugated anti‐CD19 Abs was acquired on a FACSCalibur. Cells from four murine cell lines, JAWS II, RAW 264.7, CTLL‐2, and A20, were also stained with FITC‐conjugated anti‐CD11c, PE‐conjugated anti‐CD11b, PE‐Cy5‐conjugated anti‐CD8a, and PE‐Cy7‐conjugated‐CD45R/B220 Abs, respectively, and single color flow data were collected on an LSRII. The data were fitted with a mixture of multivariate Gaussians using standard Bayesian statistical approaches and Markov chain Monte Carlo computations. Statistical mixture models were able to identify and purify major cell subsets in human peripheral blood, using an automated process that can be generalized to an arbitrary number of markers. Validation against both traditional expert gating and synthetic mixtures of murine cell lines with known mixing proportions was also performed. This article describes the studies of statistical mixture modeling of flow cytometric data, and demonstrates their utility in examples with four‐color flow data from human peripheral blood samples and synthetic mixtures of murine cell lines. © 2008 International Society for Advancement of Cytometry
Influence of milling conditions on the α‐tocopherol content of Picual olive oil
Authors: Oliveras‐López María Jesús , Granados José Javier Quesada , Bermudo Francisco Martín , de la Serrana Herminia López‐García , Martínez Maria del Carmen López 
Published: May 2008

AbstractThe aim of this study was to estimate the α‐tocopherol content in Picual extra‐virgin olive oils obtained from the 2004/2005 harvesting season and to evaluate the influence that different extraction processes and sample handling had on the final vitamin E content in the oils. A new experimental oil extraction carried out at 9 °C enabled us to obtain encouragingly high quantities of α‐tocopherol with an average quantity reaching 341.34 ± 50.17 mg/L (n = 13), with significant differences among the same oil types produced from the traditional two‐phase system at low (9 °C, p <0.01) and moderate (21.5 °C, p <0.001; 33 °C, p <0.0001) temperatures. The temperature at which extraction was carried out should be considered as a major factor to be taken into account. Additionally, we also developed a precise method for the extraction of α‐tocopherol from olive oil samples, which enables high recovery (96 ± 2%) for use in subsequent HPLC/DAD/fluorescence quantification.
Interaction between amino acid degradation, sensory attributes and lipid peroxidation in wheat rolls
Authors: Römer Julia , Majchrzak Dorota , Elmadfa Ibrahim 
Published: May 2008

AbstractThe influence of lipid peroxidation and heating duration on the amino acid pattern of wheat rolls was assessed in a model baking test. Therefore, three different types of dough were prepared including dough without any fat and two doughs with fat. To estimate the impact of lipid peroxidation products on the amino acid pattern, the two doughs containing fat were both made with rapeseed oil, one with fresh oil, the other with oxidised rapeseed oil. All kinds of dough were baked for three different duration times (18, 24 and 30 min). The lipid peroxidation status of both rapeseed oils was measured with the peroxide value and the p‐anisidine value of the unbaked fat. The amino acid content was analysed by HPLC after acid and alkaline hydrolysis. Besides determining water content and protein content, a sensory analysis was performed. Whereas the amino acid content in the dough without fat was only affected by the baking time, the doughs with rapeseed oil additionally showed a significant increase in amino acid degradation caused by lipid peroxidation products. Especially in the dough prepared with oxidised rapeseed oil, the amino acid content was partly decreased in raw dough without any heating influence. Confirming the influence of lipid peroxidation products in dough prepared with oxidised rapeseed oil, sensory analysis also showed the significantly worst overall score.
Identification of oil palm breeding lines producing oils with low acid values
Authors: Ebongue Georges Frank Ngando , Koona Paul , Nouy Bruno , Zok Simon , Carrière Frédéric , Zollo Paul‐Henri Amvam , Arondel Vincent 
Published: May 2008

AbstractIn the oil palm (Elaeis guineensis Jacq.), an active endogenous lipase is responsible for the massive release of free fatty acids (FFA) in the mesocarp of fruits at maturity. This can lead to the production of oils with unacceptable acid values. We have investigated the lipase activities in 39 genotypes of oil palm presently used in breeding programs. While most E. guineensis genotypes exhibited high lipase activity values, four of them with negligible activities were identified. We analyzed in situ lipolysis in the mesocarp upon severe wounding of fruits. The FFA content of high‐lipase fruits ranged from 17 to 55%, while all low‐lipase fruits contained less than 7.5% FFA. The analysis of oil from fallen overripe fruits indicated that all low‐lipase genotypes contained less than 1.2% FFA (oil acidity <5% FFA, FAO‐WHO international norms), while all but one high‐lipase genotypes had FFA contents much higher than the acceptable standards. Because the identified low‐lipase lines are of high agronomical value and at least one of them is an elite genotype, it will soon be possible to provide farmers with new low‐lipase oil palm lines allowing significant savings on labor costs, without any need for further breeding.
Preparation and Transmetallation of Enantioenriched α‐Aminoorganostannanes Derived from N‐Boc Phenylglycinol: Application to the Synthesis of Alafosfalin
Authors: Coeffard Vincent , Beaudet Isabelle , Evain Michel , Le Grognec Erwan , Quintard Jean‐Paul 
Published: May 2008

AbstractEnantioenriched tributylstannylated α‐amino alcohols were synthesised by an improved procedure based on ring opening of 2‐tributylstannyloxazolidines. Corresponding α‐amino organolithiums were generated from O‐silylated tributylstannylated α‐amino alcohols and trapped with retention of configuration. Thereby, this methodology was used to synthesise the antibacterial α‐aminophosphonic acid alafosfalin.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Divergent flow isoelectric focusing
Authors: Šlais Karel 
Published: May 2008

AbstractContinuous‐flow isoelectric focusing (IEF) has the potential to be an important method in proteome analysis. The current devices do not fully use the advantages of IEF, because they do not utilize all its important features including changes in background conductivity during the focusing. A novel continuous‐flow IEF method has been developed based on planar divergent flow and control of local electric field by conductivity of electrode electrolytes. A hydrophilized polypropylene nonwoven fabric was used for creation of flow and electric manifold, making the assembled device cheap, flexible and easy to set up and operate. By using the colored low‐molecular‐weight pI markers we demonstrated much higher speed of focusing in the new designed channel in comparison with a channel based on currently used rectangular geometry. The developed divergent‐flow IEF combines the speed of micro flow channels with the separation efficiency and sample load capacity of preparative devices.
Capillary electrophoresis‐time of flight‐mass spectrometry using noncovalently bilayer‐coated capillaries for the analysis of amino acids in human urine
Authors: Ramautar Rawi , Mayboroda Oleg A. , Derks Rico J. E. , van Nieuwkoop Cees , van Dissel Jaap T. , Somsen Govert W. , Deelder André M. , de Jong Gerhardus J. 
Published: May 2008

AbstractA capillary electrophoresis‐time of flight‐mass spectrometry (CE‐TOF‐MS) method for the analysis of amino acids in human urine was developed. Capillaries noncovalently coated with a bilayer of Polybrene (PB) and poly(vinyl sulfonate) (PVS) provided a considerable EOF at low pH, thus facilitating the fast separation of amino acids using a BGE of 1 M formic acid (pH 1.8). The PB–PVS coating proved to be very consistent yielding stable CE‐MS patterns of amino acids in urine with favorable migration time repeatability (RSDs <2%). The relatively low sample loading capacity of CE was circumvented by an in‐capillary preconcentration step based on pH‐mediated stacking allowing 100‐nL sample injection (i.e. ca. 4% of capillary volume). As a result, LODs for amino acids were down to 20 nM while achieving satisfactory separation efficiencies. Preliminary validation of the method with urine samples showed good linear responses for the amino acids (R2 >0.99), and RSDs for peak areas were <10%. Special attention was paid to the influence of matrix effects on the quantification of amino acids. The magnitude of ion suppression by the matrix was similar for different urine samples. The CE‐TOF‐MS method was used for the analysis of urine samples of patients with urinary tract infection (UTI). Concentrations of a subset of amino acids were determined and compared with concentrations in urine of healthy controls. Furthermore, partial least squares–discriminant analysis (PLS–DA) of the CE‐TOF‐MS dataset in the 50–450 m/z region showed a distinctive grouping of the UTI samples and the control samples. Examination of score and loadings plot revealed a number of compounds, including phenylalanine, to be responsible for grouping of the samples. Thus, the CE‐TOF‐MS method shows good potential for the screening of body fluids based on the analysis of endogenous low‐molecular weight metabolites such as amino acids and related compounds.
Difference gel electrophoresis analysis of Ras‐transformed fibroblast cell‐derived exosomes
Authors: Ji Hong , Erfani Nasrollah , Tauro Bow J. , Kapp Eugene A. , Zhu Hong‐Jian , Moritz Robert L. , Lim Justin W. E. , Simpson Richard J. 
Published: May 2008

AbstractExosomes are membrane vesicles of endocytic origin released by many cell types. The molecular composition of exosomes reflects the specialised functions of their original cells. For example, these vesicles can mediate communication through their ability to bind to target cells, facilitating processes such as vascular homeostasis and antigen presentation. Although the proteomes of exosomes from several cell types are known, exploration of exosomes from additional cell types may improve our understanding of their potential physiological roles. Here, we describe the isolation and characterisation of exosomes isolated from the culture medium of murine fibroblast NIH3T3 cells and Ras‐transformed NIH3T3 cells. The vesicular nature and size (30–100 nm) of the purified fibroblast exosomes was confirmed by electron microscopy. 2‐D difference gel electrophoresis (DIGE) was used to compare protein profiles of exosomes secreted from NIH3T3 cells and Ras‐transformed NIH3T3 cells. LC‐MS/MS sequencing identified proteins in 188 protein spots in the exosomes from the two cell lines, many of which have been previously identified in exosomes from other cell types. However, some proteins identified are novel for fibroblast exosomes, such as Serpin B6. Over 34 proteins, including milk fat globule EGF factor 8 (lactadherin), collagen α‐1 (VI), 14‐3‐3 isoforms, guanine nucleotide‐binding proteins (G proteins), the eukaryotic translation initiation factors elF‐3 γ and elF‐5A accumulated (>2‐fold) in exosomes upon Ras‐induced oncogenic transformation. Significantly, the 10.4‐fold increase in v‐Ha‐Ras p21 protein in exosomes derived from Ras‐transformed NIH3T3 cells suggests that exosome secretion may be implicated in eradication of obsolete proteins.
Effect of surface area during stabilization of electric arc furnace dusts from steel foundries
Authors: Salihoglu Guray , Pinarli Vedat 
Published: May 2008

AbstractThis study examined the effect of waste particle size on stabilization performance of hazardous electric arc furnace dusts (EAFD) from steel foundries through the measurement of the temperature rise during hydration and heavy metals leaching. EAFD was characterized by using scanning electron microscopy (SEM), X‐ray diffraction (XRD), X‐ray fluorescence (XRF), granulometry, and acid neutralization capacity (ANC) analysis. Portland cement was used to stabilize EAFD. Two types of paste samples, with EAFD content varying between 0% and 50% by weight, were prepared. The first type contained original EAFD, and the second contained ground EAFD with increased surface area. The increase in the temperatures of the mixes was monitored during the hydration reactions of the pastes. Ground EAFD yielded higher temperature rise rates than the original EAFD. Heavy metals leaching were determined by toxicity characteristics leaching procedure (TCLP). Pastes containing ground EAFD up to 50% yielded lower zinc and lead leaching than that of samples containing original EAFD. The results revealed that surface area of the EAFD may affect the stabilization performance and therefore care should be given to storage conditions at the foundries. © 2008 American Institute of Chemical Engineers Environ Prog, 2008
Characterization of collagenous matrix assembly in a chondrocyte model system
Authors: Yingst Sorcha , Bloxham Kaci , Warner Lisa R. , Brown Raquel J. , Cole Jennifer , Kenoyer Linda , Knowlton William B. , Oxford Julia Thom 
Published: May 2008

AbstractCollagen is a major component of the newly synthesized pericellular microenvironment of chondrocytes. Collagen types II, IX, and XI are synthesized and assembled into higher ordered complexes by a mechanism in which type XI collagen plays a role in nucleation of new fibrils, and in limiting fibril diameter. This study utilizes a cell line derived from the Swarm rat chondrosarcoma that allows the accumulation and assembly of pericellular matrix. Immunofluorescence and atomic force microscopy were used to assess early intermediates of fibril formation. Results indicate that this cell line synthesizes and secretes chondrocyte‐specific pericellular matrix molecules including types II, IX, and XI collagen and is suitable for the study of newly synthesized collagen matrix under the experimental conditions used. AFM data indicate that small fibrils or assemblies of microfibrils are detectable and may represent precursors of the ∼20 nm thin fibrils reported in cartilage. Treatment with hyaluronidase indicates that the dimensions of the small fibrils may be dependent upon the presence of hyaluronan within the matrix. This study provides information on the composition and organization of the newly synthesized extracellular matrix that plays a role in establishing the material properties and performance of biological materials such as cartilage. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Carbonate substituted hydroxyapatite: Resorption by osteoclasts modifies the osteoblastic response
Authors: Spence Gavin , Patel Nelesh , Brooks Roger , Rushton Neil 
Published: May 2008

AbstractCarbonate substitution within the hydroxyapatite (HA) lattice improves osteoconduction, although the mechanism by which this occurs is unclear. Discs of dense, sintered, phase‐pure HA and AB‐type carbonate substituted hydroxyapatite (CHA) were cultured for 21 days with human CD14+ cells in the presence of macrophage‐colony stimulating factor (M‐CSF) and soluble receptor activator of nuclear factor (NF)‐κB (sRANKL), during which time osteoclasts developed and resorbed the ceramic surface. Discs were then seeded with human osteoblasts (HOBs), and proliferation and collagen synthesis were measured. On some discs, the conditioned proteinaceous layer left behind by the osteoclasts was preserved. Proliferation of HOBs was increased on resorbed compared to control (unresorbed) surfaces on both materials, provided this osteoclast‐conditioned layer was left intact. Collagen synthesis by HOBs was increased on previously resorbed surfaces compared to unresorbed surfaces. This effect was seen on both materials but was seen at an earlier time point on CHA. The results suggest that osteoclasts can condition synthetic bioceramic surfaces and alter the responses of osteoblasts that subsequently populate them. Carbonate substitution may enhance osteoconduction indirectly via effects on enhanced bioresorption. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Controlled release of vanadium from titanium oxide coatings for improved integration of soft tissue implants
Authors: Jarrell John D. , Dolly Brandon , Morgan Jeffrey R. 
Published: May 2008

AbstractThis study evaluates the potential of titanium oxide coatings for short‐term delivery of vanadium for improved wound healing around implants. Titanium and vanadium oxides are bioactive agents that elicit different bioresponses in cells, ranging from implant integration and reduction of inflammation to modulation of cell proliferation and morphology. These oxides were combined in biomaterial coatings using metal‐organic precursors and rapidly screened in cell‐culture microplates to establish how vanadium‐loading influences cell proliferation and morphology. Twenty‐eight‐day elution studies indicated that there was a controlled release of vanadium from stable titanium oxide matrices. Elution profiles were mathematically modeled for vanadium loading of 20–1.25% up to a period of 28 days. Scanning electron microscopy and energy dispersive spectroscopy of the coatings indicated that the vanadium was present as a nanoscale dispersion and not segregated micron‐scale islands. The study confirmed that the observed bioresponse of cells was modulated by the soluble release of vanadium into the surrounding medium. Controlled release of vanadium from titania coatings may be used to influence soft‐tissue integration of implants by modulating cell proliferation, attachment, inflammation, and wound healing dynamics. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009