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Relevant Conditions (relevant + condition)
Selected AbstractsReduction of a Chelating Bis(NHC) Palladium(II) Complex to [{,-bis(NHC)}2Pd2H]+: A Terminal Hydride in a Binuclear Palladium(I) Species Formed under Catalytically Relevant Conditions,ANGEWANDTE CHEMIE, Issue 36 2010Peter Durch basenunterstützte Reduktion einer Palladium(II)-Vorstufe wurde der erste Palladium(I)-NHC-Komplex (NHC=N-heterocyclisches Carben) in hoher Ausbeute hergestellt und isoliert. Die Position des einzigartigen terminalen Hydridliganden (siehe Bild; PdI,cyan, H,weiß, N,blau) wurde durch Neutronenbeugung am Einkristall bestimmt, und das fluktuierende Verhalten des Komplexes in Lösung wurde untersucht. [source] A comparison of the Perinatal Society of Australia and New Zealand-Perinatal Death Classification system and relevant condition at death stillbirth classification systemsAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 5 2009Jye Ru LU Background: Stillbirths comprise two-thirds of all perinatal mortality. A classification system with low ,unexplained' stillbirth rates is important when developing prevention strategies. Aims:, This study aims to (i) determine whether the proportion of stillbirths classified as ,unexplained' is reduced, by using the relevant condition at death (ReCoDe) stillbirth classification system, compared with the Perinatal Society of Australia and New Zealand , Perinatal Death Classification (PSANZ-PDC) system; and (ii) compare the proportion of stillbirths attributed to fetal growth restriction and other causes by each system. Methods:, The ReCoDe stillbirth classification system was applied to the National Women's Health's stillbirth database for years 2004,2007. The proportion of stillbirths classified as ,unexplained' and as a result of fetal growth restriction was compared between the ReCoDe and the PSANZ-PDC systems using the ,2 test. Results:, The proportion of stillbirths classified as unexplained was less with ReCoDe compared with PSANZ-PDC (8.5% (n = 26) vs 14.1% (n = 43) P = 0.04). The proportion with the primary cause attributed to fetal growth restriction was increased with ReCoDe compared with PSANZ-PDC (23.2% (n = 71) vs 8.2% (n = 25) P < 0.0001). However, 44.8% (n = 137) of all stillbirths were small for gestational age (birthweight < 10th customised centile). The most common primary cause or condition at death by both systems was congenital abnormalities. Conclusion:, The proportion of stillbirths classified as unexplained was less with ReCoDe compared with PSANZ-PDC but rates with either method were low compared with earlier classification systems. Fetal growth restriction was listed as the primary condition more commonly with ReCoDe compared with PSANZ-PDC because of different definitions. [source] Development and evaluation of two root caries controlling programmes for home-based frail people older than 75 yearsGERODONTOLOGY, Issue 2 2008Kim Ekstrand Objectives:, (i) Initially, to devise and examine the validity of a system for determining lesion activity on root surfaces, and (ii) compare the effectiveness of two preventive programmes in controlling root caries in elderly people using the devised system. Materials and methods:, (i) Four clinical variables: texture, contour, location and colour of root caries lesions were selected to evaluate lesion activity. The intraexaminer reproducibility of the scoring system was assessed on 28 elderly patients. The accuracy was assessed on 10 of these persons using an impression material (Clinpro, 3M ESPE). (ii) Of total, 215 homebound 75+ year olds were randomly assigned to one of three groups: group 1, once a month a dental hygienist brushed the teeth of the participants and applied Duraphat vanish to active root caries lesions. The participants in groups 2 and 3 received 5000 and 1450 ppm F-toothpaste, respectively, to use twice a day. This study included an interview, a baseline examination and a final follow-up examination after 8 months. Results:, (i) Intraexaminer reproducibility of the root caries scoring system was 0.86 (Kappa). The sensitivity and specificity was 0.86 and 0.81. (ii) Data from those 189 (88%) who completed the study disclosed that there were no inter-group differences at the baseline examination concerning relevant conditions. At the end of the study, the root caries status of participants in groups 1 and 2 had improved significantly when compared with group 3 (p < 0.02). No significant difference was observed between groups 1 and 2 (p = 0.14). Conclusion:, The data suggest that the root caries scoring system is reliable. Both the intervention programmes controlled root caries development; the hygienist in eight of 10 persons, the 5000 ppm F-toothpaste in seven of 10. In contrast, five of 10 participants who only brushed with 1450 ppm F-toothpaste had root caries progression. [source] Osteoblastic Tartrate-Resistant Acid Phosphatase: Its Potential Role in the Molecular Mechanism of Osteogenic Action of Fluoride,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 10 2003K-H William Lau Abstract Although type 5 TRACP is recognized as a histochemical and biochemical marker of osteoclasts, there is evidence that bone forming cells, osteoblasts, and osteocytes also express a type 5 TRACP. Accordingly, an osteoblastic type 5 TRACP has been purified from human osteoblasts and from bovine cortical bone matrices. Comparison of biochemical properties of osteoblastic type 5 TRACP with those of osteoclastic type 5 TRACP suggests that osteoblastic type 5 TRACP is a different isoenzyme from osteoclastic type 5 TRACP. Two properties of osteoblastic type 5 TRACP may be relevant to its physiological functions: (1) it acts as a protein-tyrosine phosphatase (protein tyrosine phosphorylation) under physiologically relevant conditions, and (2) it is sensitive to inhibition by clinically relevant concentrations of fluoride. Because fluoride is a stimulator of osteoblastic proliferation and differentiation and a potent osteogenic agent and because protein tyrosine phosphorylation plays an important regulatory role in cell proliferation and differentiation, these unique properties and other evidence summarized in this review led to the proposal that the osteogenic action of fluoride is mediated, at least in part, by the fluoride-mediated inhibition of osteoblastic type 5 TRACP/protein tyrosine phosphorylation, which leads to a stimulation of osteoblast proliferation and differentiation, and subsequently, an increase in bone formation. [source] High-resolution real-time recording with microelectrode biosensors reveals novel aspects of adenosine release during hypoxia in rat hippocampal slicesJOURNAL OF NEUROCHEMISTRY, Issue 6 2003B. G. Frenguelli Abstract We have used improved miniaturized adenosine biosensors to measure adenosine release during hypoxia from within the CA1 region of rat hippocampal slices. These microelectrode biosensors record from the extracellular space in the vicinity of active synapses as they detect the synaptic field potentials evoked in area CA1 by stimulation of the afferent Schaffer collateral-commissural fibre pathway. Our new measurements demonstrate the rapid production of adenosine during hypoxia that precedes and accompanies depression of excitatory transmission within area CA1. Simultaneous measurement of adenosine release and synaptic transmission gives an estimated IC50 for adenosine on transmission in the low micromolar range. However, on reoxygenation, synaptic transmission recovers in the face of elevated extracellular adenosine and despite a post-hypoxic surge of adenosine release. This may indicate the occurrence of apparent adenosine A1 receptor desensitization during metabolic stress. In addition, adenosine release is unaffected by pharmacological blockade of glutamate receptors and shows depletion on repeated exposure to hypoxia. Our results thus suggest that adenosine release is not a consequence of excitotoxic glutamate release. The potential for adenosine A1 receptor desensitization during metabolic stress implies that its prevention may be beneficial in extending adenosine-mediated neuroprotection in a variety of clinically relevant conditions. [source] Recycling of poly(ethylene terephthalate) as polymer-polymer composites,POLYMER ENGINEERING & SCIENCE, Issue 4 2002M. Evstatiev Microfibrillar reinforced composites (MFC) comprising an isotropic matrix from a lower melting polymer reinforced by microfibrils of a higher melting polymer were manufactured under industrially relevant conditions and processed via injection molding. Low density polyethylene (LDPE) (matrix) and recycled poly(ethylene terephthalate) (PET) (reinforcing material) from bottles were melt blended (in 30/70 and 50/50 PET/LDPE wt ratio) and extruded, followed by continuous drawing, pelletizing and injection molding of dogbone samples. Samples of each stage of MFC manufacturing and processing were characterized by means of scanning electron microscopy (SEM), wide-angle X-ray scattering (WAXS), dynamic mechanical thermal analysis (DMTA), and mechanical testing. SEM and WAXS showed that the extruded blend is isotropic but becomes highly oriented after drawing, being converted into a polymer-polymer composite upon injection molding at temperatures below the melting temperature of PET. This MFC is characterized by an isotropic LDPE matrix reinforced by randomly distributed PET microfibrils, as concluded from the WAXS patterns and SEM observations. The MFC dogbone samples show impressive mechanical properties,the elastic modulus is about 10 times higher than that of LDPE and about three times higher than reinforced LDPE with glass spheres, approaching the modulus of LDPE reinforced with 30 wt% short-glass fibers (GF). The tensile strength is at least two times higher than that of LDPE or of reinforced LDPE with glass spheres, approaching that of reinforced LDPE with 30 wt% GF. The impact strength of LDPE increases by 50% after reinforcement with PET. It is concluded that: (i) the MFC approach can be applied in industrially relevant conditions using various blend partners, and (ii) the MFC concept represents an attractive alternative for recycling of PET as well as other polymers. [source] Simultaneous quantification of 2,,2,-difluorodeoxycytidine and 2,,2,-difluorodeoxyuridine nucleosides and nucleotides in white blood cells using porous graphitic carbon chromatography coupled with tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 19 2009Robert S. Jansen A novel assay for the simultaneous quantification of the widely used anticancer agent 2,,2,-difluorodeoxycytidine (gemcitabine; dFdC), its deaminated metabolite 2,,2,-difluorodeoxyuridine (dFdU) and their mono-, di- and triphosphates (dFdCMP, dFdCDP, dFdCTP, dFdUMP, dFdUDP and dFdUTP) in peripheral blood mononuclear cells (PBMCs) is described. Separation of all eight compounds was achieved within 15,min using a porous graphitic carbon column (Hypercarb) with a gradient from 0 to 25,mM ammonium bicarbonate in acetonitrile/water (15:85, v/v). Calibration ranges in PBMC lysate from 4.29 to 429, 29.0 to 2900, 31.4 to 3140 and 36.9 to 3690,nM for dFdC, dFdCMP, dFdCDP and dFdCTP and from 42.1 to 4210, 25.4 to 2540, 43.2 to 4320 and 52.7 to 5270,nM for dFdU, dFdUMP, dFdUDP and dFdUTP, respectively, were validated. Accuracies were within 82.3,119% at the lower limit of quantification (LLOQ) and the precisions were less than 20.0%. At the other tested levels accuracies were within 91.4,114% and precisions less than 14.9%. Mixtures of 13C,15N2 -labeled dFdC and dFdU nucleotides were synthesized and used as internal standards. Whole blood samples showed extensive ongoing dFdC metabolism when stored at room temperature, but not on ice-water, which made the addition of enzyme inhibitors unnecessary. Stock solutions and samples were stable under all analytically relevant conditions. The method was successfully applied to clinical samples. Copyright © 2009 John Wiley & Sons, Ltd. [source] ,-Sheet aggregation of kisspeptin-10 is stimulated by heparin but inhibited by amphiphilesBIOPOLYMERS, Issue 8 2010Søren B. Nielsen Abstract The murine 10-residue neurohormone kisspeptin (YNWNSFGLRY) is an important regulator of reproductive behavior and gonadotrophin secretion. It is known to form a random coil in solution, but undergoes a structural change in the presence of membranes although the nature of this change is not fully determined. The peptide's conformational versatility raises the question whether it is also able to form ordered aggregates under physiological conditions, which might be relevant as a storage mechanism. Here we show that heparin induces kisspeptin to form ,-sheet rich amyloid aggregates both at neutral (pH 7.0) and slightly acidic (pH 5.2) conditions. Addition of heparin leads to aggregation after a certain lag phase, irrespective of the time of addition of heparin, indicating that heparin is needed to facilitate the formation of fibrillation nuclei. Aggregation is completely inhibited by submicellar concentrations of zwitterionic and anionic surfactants. Unlike previous reports, our NMR data do not indicate persistent structure in the presence of zwitterionic surfactant micelles. Thus kisspeptin can aggregate under physiologically relevant conditions provided heparin is present, but the process is highly sensitive to the presence of amphiphiles, highlighting the very dynamic nature of the peptide conformation and suggesting that kisspeptin aggregation is a biologically regulatable process. © 2010 Wiley Periodicals, Inc. Biopolymers 93: 678,689, 2010. 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 [source] Mechanistic model for prediction of formate dehydrogenase kinetics under industrially relevant conditionsBIOTECHNOLOGY PROGRESS, Issue 1 2010T. Schmidt Abstract Formate dehydrogenase (FDH) from Candida boidinii is an important biocatalyst for the regeneration of the cofactor NADH in industrial enzyme-catalyzed reductions. The mathematical model that is currently applied to predict progress curves during (semi-)batch reactions has been derived from initial rate studies. Here, it is demonstrated that such extrapolation from initial reaction rates to performance during a complete batch leads to considerable prediction errors. This observation can be attributed to an invalid simplification during the development of the literature model. A novel mechanistic model that describes the course and performance of FDH-catalyzed NADH regeneration under industrially relevant process conditions is introduced and evaluated. Based on progress curve instead of initial reaction rate measurements, it was discriminated from a comprehensive set of mechanistic model candidates. For the prediction of reaction courses on long time horizons (>1 h), decomposition of NADH has to be considered. The model accurately describes the regeneration reaction under all conditions, even at high concentrations of the substrate formate and thus is clearly superior to the existing model. As a result, for the first time, course and performance of NADH regeneration in industrial enzyme-catalyzed reductions can be accurately predicted and used to optimize the cost efficiency of the respective processes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Osmium(II) and Ruthenium(II) Arene Maltolato Complexes: Rapid Hydrolysis and Nucleobase BindingCHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2007Abstract Density functional calculations show that aquation of [Os(,6 -arene)(XY)Cl]n+ complexes is more facile for complexes in which XY=an anionic O,O-chelated ligand compared to a neutral N,N-chelated ligand, and the mechanism more dissociative in character. The O,O-chelated XY=maltolato (mal) [M(,6 - p -cym)(mal)Cl] complexes, in which p -cym=p -cymene, M=OsII (1) and RuII (2), were synthesised and the X-ray crystal structures of 1 and 2,2,H2O determined. Their hydrolysis rates were rapid (too fast to follow by NMR spectroscopy). The aqua adduct of the OsII complex 1 was 1.6,pKa units more acidic than that of the RuII complex 2. Dynamic NMR studies suggested that O,O-chelate ring opening occurs on a millisecond timescale in coordinating proton-donor solvents, and loss of chelated mal in aqueous solution led to the formation of the hydroxo-bridged dimers [(,6 - p -cym)M(,-OH)3M(,6 - p -cym)]+. The proportion of this dimer in solutions of the OsII complex 1 increased with dilution and it predominated at micromolar concentrations, even in the presence of 0.1,M NaCl (conditions close to those used for cytotoxicity testing). Although 9-ethylguanine (9-EtG) binds rapidly to OsII in 1 and more strongly (log,K=4.4) than to RuII in 2 (log,K=3.9), the OsII adduct [Os(,6 - p -cym)(mal)(9EtG)]+ was unstable with respect to formation of the hydroxo-bridged dimer at micromolar concentrations. Such insights into the aqueous solution chemistry of metal,arene complexes under biologically relevant conditions will aid the rational design of organometallic anticancer agents. [source] | ||||||||||||||||