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Lower Activity (lower + activity)
Terms modified by Lower Activity Selected AbstractsOlefins as Steering Ligands for Homogeneously Catalyzed HydrogenationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2004Pascal Maire Abstract Iridium(I) complexes containing a (5H -dibenzo[a,d]cyclohepten-5-yl)-phosphane (troppR; R = phosphorus-bound substituent = Ph, Cyc) as a rigid, concave-shaped, mixed phosphane olefin ligand were prepared and tested as catalyst precursors in the hydrogenation of imines. With the complex [Ir(troppCyc)(cod)]OTf, turnover frequencies (TOFs) of >6000 h,1 were reached in the hydrogenation of N -phenyl-benzylidenamine, PhNCHPh. Lower activities (TOF>80 h,1) are observed with N -phenyl-(1-phenylethylidene)amine, PhNCMePh. Chiral tropp-type ligands were prepared in few simple steps. Monosubstitution of the olefinic unit in the dibenzo[a,d]cycloheptenyl moiety with (R)- or (S)-mentholate gave mixtures of diastereomers that could be separated and isolated in enantiomerically pure form. Iridium(I) complexes with these ligands are rare examples of side-on bonded enolether complexes. In catalytic imine hydrogenations, complete conversion (>98,%) was reached in all cases (conditions: p[H2] = 50 bar, T = 50,°C, t = 2 h, substrate/catalyst 100:1). The best enantiomeric excess (ee = 86,% S isomer) was reached with PhNCMePh as substrate and the R,R form of the (10-menthyloxy-5H -dibenzo[a,d]cyclohepten-5-yl)diphenylphosphane ligand. The iridium(I) complex containing the same phosphane gave a 60,% ee (S isomer) with the enamide N-(1-phenylvinyl)acetamide as substrate (conditions: p[H2] = 4 bar, T = 50,°C, t = 18 h, substrate/catalyst = 50:1). These reactions constitute the first examples in which chiral olefins have been used as steering ligands in catalytic enantioselective hydrogenations. [source] Oral health care status of homebound elderly in JapanJOURNAL OF ORAL REHABILITATION, Issue 8 2001Masayuki Morishita We examined the present conditions of oral health care in order to contribute towards an effective system to provide oral health care for homebound elderly in Japan. A questionnaire was mailed to homebound elderly subjects (n=908) and returned by mail. A 73·6% response was achieved. The questionnaire was designed to elicit information with respect to the general condition of the subjects and independence of oral health care. About 70% of the subjects were chair- or bed-bound. Among all subjects, 37·6% required partial or full assistance on toothbrushing, 55·6% on cleaning dentures and 46·7% on eating. The degree of oral health care tended to be poor for chair- or bed-bound elderly compared with independent or house-bound elderly. Homebound elderly with lower Activities of Daily Living Scale (ADL) required more support for oral health care compared with elderly with higher ADL. [source] Effect of methylxanthines on production of cellulases by Penicillium echinulatumJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2007M. Camassola Abstract Aim:, In this work, the effect of supplementing liquid cellulase production media (CPM) with methylxanthines (aminophylline, caffeine and theophylline), with and without the addition of glucose, on the secretion of cellulases by Penicillium echinulatum strain 2HH (wild-type) and the derived mutant strain 9A02S1 was studied. Methods and Results:, When compared with unsupplemented CPM, both strains produced higher , -glucosidase and filter paper activities (FPAs) in CPM supplemented with 1 ,mol l,1 of caffeine but lower activities with 5 ,mol l,1 of caffeine. With theophylline only, strain 9A02S1 produced higher , -glucosidase and FPAs, while aminophylline produced no effect on the cellulase activity of either strain. Supplementation of CPM with 0·5% (w/v) of glucose plus caffeine resulted in higher , -glucosidase and FPAs being produced by strain 2HH, but not strain 9A02S1, than in CPM supplemented with 0·5% (w/v) of glucose only. Conclusions:, These results indicate that different concentrations of caffeine and theophylline can increase the , -glucosidase and FPAs produced by P. echinulatum strains 2HH and 9A02S1. Significance and Impact of the Study:, The results suggest that some methylxanthines, in adequate concentration, can be used as media components to increase cellulase production. [source] Casearin X, Its Degradation Product and Other Clerodane Diterpenes from Leaves of Casearia sylvestris: Evaluation of Cytotoxicity against Normal and Tumor Human CellsCHEMISTRY & BIODIVERSITY, Issue 1 2010André Gonzaga, Santos Abstract An EtOH extract of the leaves of Casearia sylvestris afforded new clerodane diterpene, casearin X, together with the known compounds casearins B, D, L, and O, and caseargrewiin F. Casearin X degraded to the corresponding dialdehyde when stored in CDCl3. The diterpenes isolated were cytotoxic to human cancer cell lines, with caseargrewiin F being the most active and the new clerodane, casearin X, the second active compound with IC50 values comparable to the positive control doxorubicin. All isolated diterpenes showed lower activities against normal human cells than against cancer cell lines, which might indicate a possible selective action on cancer cells. Casearin X dialdehyde was not cytotoxic to cancer cells indicating that the occurrence of these CO groups at C(18) and C(19) is incompatible with the cytotoxic activity. [source] Size-related differences in diel activity of two species of juvenile eel (Anguilla) in a laboratory streamECOLOGY OF FRESHWATER FISH, Issue 4 2000G. J. Glova Abstract , The diel activity of three size groups (small=<100 mm; medium=100,199 mm; large=200,299 mm total length) of juvenile shortfinned ("shortfin") eels (Anguilla australis) and longfinned ("longfin") eels (A. dieffenbachii) was tested in a laboratory flow tank over a 48-h period during summer. All size groups of both species were nocturnally active, with the eels hiding in the substratum during the day and coming out on top of the cobbles from dusk to dawn, to feed. During the foraging period, the numbers and activity of all sizes of longfins visible were greater than those seen of shortfins, with the differences being more pronounced for small and medium eels. The activity of all eels consisted mostly of foraging by crawling, searching and probing for prey among the cobbles. Rate of activity increased with size of eel for both species. Small eels of either species did more swimming than eels of the larger sizes, whereas large eels were observed more frequently with only their head out of the substrate than were the smaller individuals. Feeding of small eels within the interstitial spaces of the streambed may explain their significantly lower activity on top of the substrate at night. The significantly lower rate of activity recorded for shortfins than longfins of all sizes may be due partly to their ability to feed within the interstices of the stream bed, and (or) longer time to recover from handling and habituate to the test environment., [source] Levels of pre-kallikrein in resting and stimulated human parotid and submandibular salivaEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 5 2001Carol A. Francis Salivary tissue kallikrein is stored in an active form in human salivary glands. Pre-kallikrein has been demonstrated in mixed saliva, but it is not clear if the various salivary glands contribute equally. This study set out to determine if pre-kallikrein is present in human parotid and submandibular salivas at rest, whether levels change during stimulation, and to compare the pattern of pre-kallikrein and kallikrein secretion with that of total protein. Resting and citric acid-stimulated parotid and submandibular, and gum-stimulated parotid saliva samples were collected from 6 healthy subjects. Salivary flows were determined gravimetrically. Total protein concentration and kallikrein enzymic activity were assayed using standard techniques. Pre-kallikrein was assayed following trypsinisation of duplicate samples. Pre-kallikrein was present in parotid and submandibular ductal saliva. Proportions of pre-kallikrein and active kallikrein were similar in salivas secreted at rest and during stimulation, and both outputs mirrored protein output in both major glands. Gum-stimulated parotid saliva showed lower activity than resting, and no differences were seen between resting and stimulated submandibular samples. [source] Experimental validation of metabolic pathway modelingFEBS JOURNAL, Issue 13 2008An illustration with glycolytic segments from Entamoeba histolytica In the search for new drug targets in the human parasite Entamoeba histolytica, metabolic control analysis was applied to determine, experimentally, flux control distribution of amebal glycolysis. The first (hexokinase, hexose-6-phosphate isomerase, pyrophosphate-dependent phosphofructokinase (PPi -PFK), aldolase and triose-phosphate isomerase) and final (3-phosphoglycerate mutase, enolase and pyruvate phosphate dikinase) glycolytic segments were reconstituted in vitro with recombinant enzymes under near-physiological conditions of pH, temperature and enzyme proportion. Flux control was determined by titrating flux with each enzyme component. In parallel, both glycolytic segments were also modeled by using the rate equations and kinetic parameters previously determined. Because the flux control distribution predicted by modeling and that determined by reconstitution were not similar, kinetic interactions among all the reconstituted components were experimentally revised to unravel the causes of the discrepancy. For the final segment, it was found that 3-phosphoglycerate was a weakly competitive inhibitor of enolase, whereas PPi was a moderate inhibitor of 3-phosphoglycerate mutase and enolase. For the first segment, PPi was both a strong inhibitor of aldolase and a nonessential mixed-type activator of amebal hexokinase; in addition, lower Vmax values for hexose-6-phosphate isomerase, PPi -PFK and aldolase were induced by PPi or ATP inhibition. It should be noted that PPi and other metabolites were absent from the 3-phosphoglycerate mutase and enolase or aldolase and hexokinase kinetics experiments, but present in reconstitution experiments. Only by incorporating these modifications in the rate equations, modeling predicted values of flux control distribution, flux rate and metabolite concentrations similar to those experimentally determined. The experimentally validated segment models allowed ,in silico experimentation' to be carried out, which is not easy to achieve in in vivo or in vitro systems. The results predicted a nonsignificant effect on flux rate and flux control distribution by adding parallel routes (pyruvate kinase for the final segment and ATP-dependent PFK for the first segment), because of the much lower activity of these enzymes in the ameba. Furthermore, modeling predicted full flux-control by 3-phosphoglycerate mutase and hexokinase, in the presence of low physiological substrate and product concentrations. It is concluded that the combination of in vitro pathway reconstitution with modeling and enzyme kinetics experimentation permits a more comprehensive understanding of the pathway behavior and control properties. [source] Site-directed mutagenesis of the active site loop of the rhodanese-like domain of the human molybdopterin synthase sulfurase MOCS3FEBS JOURNAL, Issue 11 2007Major differences in substrate specificity between eukaryotic, bacterial homologs Sequence alignments of human molybdopterin synthase sulfurase, MOCS3, showed that the N-terminal domain is homologous to Escherichia coli MoeB, whereas the C-terminal domain is homologous to rhodanese-like proteins. Previous studies showed that the activity of the separately purified rhodanese-like domain of MOCS3 displayed 1000-fold lower activity in comparison to bovine rhodanese with thiosulfate as sulfur source. When the six amino acid active site loop of MOCS3 rhodanese-like domain was exchanged with the loop found in bovine rhodanese, thiosulfate:cyanide sulfurtransferase activity was increased 165-fold. Site-directed mutagenesis of each individual residue of the active site loop of the MOCS3 rhodanese-like domain showed that the charge of the last amino acid determines thiosulfate sulfurtransferase activity. Replacing Asp417 by threonine resulted in 90-fold increased activity, whereas replacing it by arginine increased the activity 470-fold. Using a fully defined in vitro system containing precursor Z, MOCS2A, E. coli MoaE, E. coli MoeB, Mg-ATP, MOCS3 rhodanese-like domain, and thiosulfate, it was shown that sulfur transfer to MOCS2A was also affected by the alterations, but not as drastically. Our studies revealed that in humans and most eukaryotes thiosulfate is not the physiologic sulfur donor for MOCS3, whereas in bacterial homologs, which have an arginine at the last position of the active site loop, thiosulfate can be used as a sulfur source for molybdenum cofactor biosynthesis. The phylogenetic analysis of MoeB homologs showed that eukaryotic homologs are of bacterial origin. Furthermore, it could be shown that an MoeB homolog named MoeZ, where the dual CXXC zinc-binding motif of the MoeB domain is not present, arose independently several times during evolution. [source] Conversion of a glutamate dehydrogenase into methionine/norleucine dehydrogenase by site-directed mutagenesisFEBS JOURNAL, Issue 22 2001Xing-Guo Wang In earlier attempts to shift the substrate specificity of glutamate dehydrogenase (GDH) in favour of monocarboxylic amino-acid substrates, the active-site residues K89 and S380 were replaced by leucine and valine, respectively, which occupy corresponding positions in leucine dehydrogenase. In the GDH framework, however, the mutation S380V caused a steric clash. To avoid this, S380 has been replaced with alanine instead. The single mutant S380A and the combined double mutant K89L/S380A were satisfactorily overexpressed in soluble form and folded correctly as hexameric enzymes. Both were purified successfully by Remazol Red dye chromatography as routinely used for wild-type GDH. The S380A mutant shows much lower activity than wild-type GDH with glutamate. Activities towards monocarboxylic substrates were only marginally altered, and the pH profile of substrate specificity was not markedly altered. In the double mutant K89L/S380A, activity towards glutamate was undetectable. Activity towards l -methionine, l -norleucine and l -norvaline, however, was measurable at pH 7.0, 8.0 and 9.0, as for wild-type GDH. Ala163 is one of the residues that lines the binding pocket for the side chain of the amino-acid substrate. To explore its importance, the three mutants A163G, K89L/A163G and K89L/S380A/A163G were constructed. All three were abundantly overexpressed and showed chromatographic behaviour identical with that of wild-type GDH. With A163G, glutamate activity was lower at pH 7.0 and 8.0, but by contrast higher at pH 9.0 than with wild-type GDH. Activities towards five aliphatic amino acids were remarkably higher than those for the wild-type enzyme at pH 8.0 and 9.0. In addition, the mutant A163G used l -aspartate and l -leucine as substrates, neither of which gave any detectable activity with wild-type GDH. Compared with wild-type GDH, the A163 mutant showed lower catalytic efficiencies and higher Km values for glutamate/2-oxoglutarate at pH 7.0, but a similar kcat/Km value and lower Km at pH 8.0, and a nearly 22-fold lower S0.5 (substrate concentration giving half-saturation under conditions where Michaelis,Menten kinetics does not apply) at pH 9.0. Coupling the A163G mutation with the K89L mutation markedly enhanced activity (100,1000-fold) over that of the single mutant K89L towards monocarboxylic amino acids, especially l -norleucine and l -methionine. The triple mutant K89L/S380A/A163G retained a level of activity towards monocarboxylic amino acids similar to that of the double mutant K89L/A163G, but could no longer use glutamate as substrate. In terms of natural amino-acid substrates, the triple mutant represents effective conversion of a glutamate dehydrogenase into a methionine dehydrogenase. Kinetic parameters for the reductive amination reaction are also reported. At pH 7 the triple mutant and K89L/A163G show 5 to 10-fold increased catalytic efficiency, compared with K89L, towards the novel substrates. In the oxidative deamination reaction, it is not possible to estimate kcat and Km separately, but for reductive amination the additional mutations have no significant effect on kcat at pH 7, and the increase in catalytic efficiency is entirely attributable to the measured decrease in Km. At pH 8 the enhancement of catalytic efficiency with the novel substrates was much more striking (e.g. for norleucine ,,2000-fold compared with wild-type or the K89L mutant), but it was not established whether this is also exclusively due to more favourable Michaelis constants. [source] Functional analysis of promoter variants in the microsomal triglyceride transfer protein (MTTP) gene,HUMAN MUTATION, Issue 1 2008Diana Rubin Abstract The microsomal triglyceride transfer protein (MTTP) is required for the assembly and secretion of apolipoprotein B (apoB)-containing lipoproteins from the intestine and liver. According to this function, polymorphic sites in the MTTP gene showed associations to low-density lipoprotein (LDL) cholesterol and related traits of the metabolic syndrome. Here we studied the functional impact of common MTTP promoter polymorphisms rs1800804:T>C (,164T>C), rs1800803:A>T (,400A>T), and rs1800591:G>T (,493G>T) using gene-reporter assays in intestinal Caco-2 and liver Huh-7 cells. Significant results were obtained in Huh-7 cells. The common MTTP promoter haplotype ,164T/,400A/,493G showed about two-fold lower activity than the rare haplotype ,164C/,400T/,493T. MTTP promoter mutant constructs ,164T/,400A/,493T and ,164T/,400T/,493T exhibited similar activity than the common haplotype. Activities of mutants ,164C/,400A/,493G and ,164C/,400A/,493T resembled the rare MTTP promoter haplotype. Electrophoretic mobility shift assays (EMSAs) revealed higher binding capacity of the transcriptional factor Sterol regulatory element binding protein1a (SREBP1a) to the ,164T probe in comparison to the ,164C probe. In conclusion, our study indicates that the polymorphism ,164T>C mediates different activities of common MTTP promoter haplotypes via SREBP1a. This suggested that the already described SREBP-dependent modulation of MTTP expression by diet is more effective in ,164T than in ,164C carriers. Hum Mutat 29(1), 123,129, 2008. © 2007 Wiley-Liss, Inc. [source] Explaining trading volume in the euroINTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 1 2006Janusz Brzeszczynski Abstract Following the introduction of the euro in 1999, daily trade volume began a downward trend until early 2002, after which daily volume started to trend upward. A model of weekly trades suggests that changes in momentum as well as the carry trade motives of interest differentials are significant explanatory factors. Daily data examination reveals that Fridays have lower activity, and Tuesdays greater activity than average. At the intradaily level, trading is very low before and after London business hours. Within the London business day, trade activity is higher in 5-min intervals when a ,big figure' is breached. This is consistent with stop-loss or take-profit motives for trading. Copyright © 2006 John Wiley & Sons, Ltd. [source] Bismuth-Doped Ceria, Ce0.90Bi0.10O2: A Selective and Stable Catalyst for Clean Hydrogen CombustionADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009Jurriaan Beckers Abstract Bismuth-doped cerias are successfully applied as solid "oxygen reservoirs" in the oxidative dehydrogenation of propane. The lattice oxygen of the ceria is used to selectively combust hydrogen from the dehydrogenation mixture at 550,°C. This process has three key advantages: it shifts the dehydrogenation equilibrium to the desired products side, generates heat, aiding the endothermic dehydrogenation, and simplifies product separation (water vs. hydrogen). Furthermore, the process is safer, since it uses the catalyst's lattice oxygen instead of gaseous oxygen. We show here that bismuth-doped cerias are highly active and stable towards hydrogen combustion, and explore four different approaches for optimising their application in the oxidative dehydrogenation of propane: first, the addition of extra hydrogen which lowers hydrocarbon conversion by suppressing both combustion and coking; second, the addition of tin which completely inhibits coking; third, the addition of platinum which increases selectivity, but at the expense of lower activity. The best results are obtained through tuning the reaction temperature. At 400,°C, high activity and selectivity were obtained for the bismuth-doped ceria Ce0.90Bi0.10O2. Here, 90% of the hydrogen feed is converted at 98% selectivity. This optimal reaction temperature can be rationalised from the hydrogen and propene temperature-programmed reduction (TPR) profiles: 400,°C lies above the reduction maximum of hydrogen, yet below that of propene. That is, this temperature is sufficiently high to facilitate rapid hydrogen combustion, but low enough to prevent hydrocarbon conversion. [source] The Immobilization of Rhodium-4-(diphenylphosphino)-2- (diphenylphosphinomethyl)-pyrrolidine (Rh-PPM) Complexes: A Systematic StudyADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 12-13 2006Benoît Pugin Abstract A modular toolbox for the immobilization of homogeneous catalysts to various supports is described. It consists of functionalized chiral diphosphines and three different linkers based on isocyanate chemistry and it is used to attach the 4-(diphenylphosphino)-2-(diphenylphosphinomethyl)-pyrrolidine (PPM) ligand to a large variety of soluble, swellable and non-swellable solid organic polymers and to silica gels. As model reaction the hydrogenation of acetamidocinnamic acid derivatives, catalyzed with high enantioselectivity was chosen. Besides information on the usefulness of a particular type of support for synthetic applications, the experiments were also designed to address the question how parameters such as solubility, swellability, cage or pore size and solvent affect the rate and enantioselectivity of an immobilized catalyst. Rhodium complexes of ligands attached to soluble polymers and inorganic supports achieved ees up to 95,% and turnover frequencies between 700 and 1400,h,1, very close to the values of the homogeneous Rh catalyst (ee 95,%, TOF 1320,h,1). Insoluble or strongly cross-linked organic polymers led to catalysts with lower enantioselectivity and activity. PPM ligands attached to water soluble dendrimer fragments allowed hydrogenation in water solution with ees up to 94,%, albeit with much lower activity compared to reactions in methanol with the homogeneous catalyst. [source] Effect of an organic acid blend and phytase added to a rapeseed cake-containing diet on performance, intestinal morphology, caecal microflora activity and thyroid status of broiler chickensJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1 2010S. Smulikowska Summary The experiment was carried out on 96 female broilers, allocated to eight groups of 12 birds kept in individual cages. Two basal wheat- and soyabean meal-based diets containing 150 g/kg of rapeseed expeller cake were formulated, differing in the level of P: 7.1 g/kg in diet H or 5.9 g/kg in diet L. Rapeseed cake supplied 3.15 ,mol alkenyl glucosinolates per gram of diet. The eight treatments were: basal diets only, basal diets + phytase (1000 U/kg), basal diets + organic acid blend (OA, 6 g/kg), or basal diets + both additives. Diets were fed from day 8 to 28 of life. The results showed that the lower dietary P content and OA supplementation did not significantly affect feed intake or BWG, while both increased (p < 0.001) after phytase supplementation. Tibia ash content as well as tibia ultimate strength were lower (p < 0.001) in birds fed diets L compared with diets H, and increased (p < 0.01) with phytase supplementation of diet L, while OA had no influence on either parameter. Dietary P levels and OA supplementation had no influence on the pH of gut digesta, but the pH of jejunal digesta increased following phytase supplementation (p < 0.01). Morphological measurements of the small intestinal mucosa of chicks indicated that OA added to diet L depressed villi height (p < 0.001) and crypt depth (p < 0.001); both parameters increased after phytase supplementation (p < 0.01). The lower total SCFA as well as acetic, propionic and butyric acid concentrations in caecal digesta indicated lower activity of caecal microflora in birds fed diets L compared with H. OA supplementation had no influence, while phytase supplementation increased the concentration of acetic acid in caecal digesta. Supplementation of diets with either phytase or OA increased thyroid weight by 16% (p < 0.01) and 11% (p < 0.05) respectively. The increase in thyroid weight because of phytase supplementation was greater at the lower dietary P level, and the greatest when both phytase and OA were added to the diet. [source] Effect of cyclosporin A in Lewis rats in vivo and HeLa cells in vitroJOURNAL OF APPLIED TOXICOLOGY, Issue 3 2002Andrea Sovcikova Abstract The aim of this study was to compare the effect of cyclosporin A (CsA) in inbred Lewis rats with published assessment of immunotoxicity in ,classical' outbred Wistar rats. A second purpose was to consider the contribution of a panel of in vitro assays in cell cultures when added to an immunotoxicity study in vivo. The in vivo effect of CsA was investigated in a 28-day subacute immunotoxicity study in male Lewis rats at three different concentrations: 1.25, 5 and 20 mg kg,1. The highest dose of CsA exceeded the maximum tolerated dose. A drop in body, spleen and popliteal lymph node weight of exposed animals displayed symptoms of toxicity. At a high toxic dose, haematological changes showed a decrease in the leucocyte count and in the percentage of lymphocytes, and an increase in the percentage of polymorphonuclear leucocytes. The haematocrit was significantly dose-dependently suppressed in all rats exposed to CsA. A similar dose-dependent depression of the mean cell volume of erythrocytes was found in rats given high and middle doses of CsA. The phagocytic activity of polymorphonuclear leucocytes and monocytes also was significantly dose-dependently suppressed. No significant changes in primary antibody response to sheep erythrocytes or in vitro proliferative response of spleen lymphocytes to mitogens were found in those rats. A battery of in vitro cytotoxicity methods was selected for the evaluation of metabolic and functional activity of subcellular organelles (mitochondria, lysosomes) and for the detection of drug-induced superoxide-mediated damage in HeLa cells. This cell line was chosen because it has a lower activity of superoxide dismutase (SOD) than normal cells and is sufficiently sensitive for the detection of the induction of oxygen radicals. The in vitro results indicated a direct relationship between CsA cytotoxicity and a change in the mitochondrial enzyme activity, as well as an induction of superoxide production. The results of the study indicated that a combination of selected in vivo and in vitro methods is an inexpensive way to obtain more complex information on cell status affected by xenobiotics. Copyright © 2002 John Wiley & Sons, Ltd. [source] Alkaline phosphatase isozyme activity in serum from patients with chronic periodontitisJOURNAL OF PERIODONTAL RESEARCH, Issue 4 2003P. Gibert Background:, High alkaline phosphatase activity (ALP) is shown in the periodontal ligament due to the constant renewal of this tissue or pathological circumstances. We have previously shown that the activity level of this enzyme could be reflected at the serum level. Objectives:, Because the local production of ALP in the periodontal ligament is often of the bone-type enzyme, we studied the activity of this isozyme among the other isoforms in the serum of patients with chronic periodontitis in comparison with that of control subjects. Material and methods:, This study included 83 patients (59 with periodontal disease, 24 as control group) and we determined the total seric ALP activity and the percentage of the different isoforms (essentially bone, kidney and intestinal-types) by Ektachem analyser and gel agarose electrophoresis respectively. Conclusions:, By comparisons between the two groups, our results showed a relationship between loss of attachment in periodontal disease and a drop in bone ALP activity in serum. Moreover, these results suggested a gender based difference as well, with lower activity more frequent in women than in men. [source] Haptoglobin from psoriatic patients exhibits decreased activity in binding haemoglobin and inhibiting lecithin-cholesterol acyltransferase activityJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 4 2008L Cigliano Abstract Objective, The aim of this work was to assess whether psoriasis is associated with phenotype prevalence and altered activity of haptoglobin (Hpt). Background, Hpt is a plasma acute-phase glycoprotein, displaying in humans three phenotypes. Phenotype prevalence or structure modification of Hpt was associated with several diseases. The Hpt main function is to bind and carry to the liver free haemoglobin for degradation and iron recycling. Hpt was recently found able to bind the apolipoprotein A-I (ApoA-I), thus impairing its stimulation on the activity of the enzyme lecithin-cholesterol acyl-transferase (LCAT). Study design, Hpt was isolated from patients with psoriasis vulgaris, and its activity in haemoglobin or ApoA-I binding and LCAT inhibition was compared with that of normal protein. Methods, Two affinity chromatography steps, the first using resin-coupled haemoglobin and the second anti-Hpt antibodies, were used to purify Hpt. The protein phenotype was assessed by electrophoresis. Binding experiments were performed by Enzyme-linked immunosorbent assay with stationary haemoglobin or ApoA-I, Hpt in solution and anti-Hpt antibodies for detection of bound Hpt. Standard LCAT assays were carried out in the presence of Hpt purified from patients or healthy subjects. Results, Phenotype prevalence of Hpt in psoriasis was not found. After affinity chromatography by haemoglobin, albumin and ApoA-I were routinely found heavily contaminating only Hpt from normal subjects. Isolated Hpt from patients had lower activity than normal protein in both haemoglobin binding and LCAT inhibition. Conclusions, In psoriasis, Hpt displays some structure modification(s), which might be associated with the protein function in the disease. [source] Mathematical Modeling of Homopolymerization on Supported Metallocene CatalystsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2004Alessio Alexiadis Abstract Summary: In this paper, a mathematical model describing olefin polymerization with metallocene catalysts is presented. It is an improvement of a previous model, the "particle growth model" (PGM) proposed by, among others, one of the authors of the present work and derives from the so-called "multigrane model" (MGM). The main differences between this work and others is a more sophisticated approach to fragmentation with respect to the MGM. Additionally, there is a more specific modeling for the unfragmented core with respect to the PGM. The numerical results obtained by the model are compared with experimental data. The results of this work allow to extend the PGM to catalysts with lower activity. The importance of those catalysts depends on the fact that high activity catalysts could bring, in some cases, too poor polymer morphology. Geometrical representation of the micro- and macroparticle. [source] Insecticidal activity of N -arylalkylbenzhydrolpiperidinesPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 12 2002Joel M Wierenga Abstract Benzhydrolpiperidine (BZP) insecticides represent a novel class of chemistry. Their specificity and efficacy as well as their low mammalian toxicity give them excellent potential for commercialization. Several N -arylalkylbenzhydrolpiperidines were tested for activity against a variety of insects in the laboratory and greenhouse. These tests were used to select compounds for field trials and determine rates of application for field tests. The BZP compounds have good activity against Lepidoptera, with modest Coleoptera activity. They are toxic by oral administration and have about 100-fold lower activity by topical exposure. A methyl carbamate BZP, F4265, was the most active compound, with LC50 values of 6,mg,litre,1 or less for most Lepidopteran species tested. F4265 was active in a variety of field trials at 112,224,g,AI,ha,1. Whole-plant testing methods conducted in the greenhouse were effective in determining field test rates. © 2002 Society of Chemical Industry [source] Enzyme activity of the phenylpropanoid pathway as a response to apple scab infectionANNALS OF APPLIED BIOLOGY, Issue 3 2010A. Slatnar The study was performed on apple trees, ,Golden Delicious' cv., which is a scab-susceptible cultivar. The phenolic content of apple fruit was determined in different parts of the peel. The phenolic compounds were analysed in the scab spot, in the tissue around the spot and in the healthy tissue. We determined the concentration of various phenolic compounds and related enzyme activities. Infection with the Venturia inaequalis fungus enhanced the metabolism of phenolic compounds at the scab spot, around the spot and in healthy peel. Compared with the healthy tissue and the tissue around the spot, the scab spot showed higher enzyme activity for all tested enzymes, except for dihydrochalcone 2,- O -glucosyltransferase, which had lower activity in the scab spot. In comparison to the healthy peel, the scab spot showed up to 3.4 times more hydroxycinnamic acids, up to 1.1 times more dihydrochalcones and up to 1.4 times more flavan-3-ols. In contrast, the healthy peel showed up to 1.6 times more flavonols than the scab spot. [source] Phagocytosis of heat-killed Staphylococcus aureus by eosinophils: comparison with neutrophilsAPMIS, Issue 2 2009YASUKO HATANO Eosinophils are characterized by several functional properties, such as chemotaxis, adhesion, superoxide anion production, and degranulation. In this article, we have studied the role of bacterial ingestion by eosinophils in comparison with that by neutrophils. Eosinophils and neutrophils were purified by using the Percoll gradient method followed by selection with CD16-coated immunomagnetic beads and centrifugation through a Ficoll-Hypaque gradient combined with dextran sedimentation, respectively. Both cells were preincubated with anti-Fc,RIIa mAb (CD32 mAb), anti-Fc,RIIIb mAb (CD16 mAb), anti-CR3 (CD11b mAb), or anti-CR1 (CD35 mAb) before being examined for phagocytosis of opsonized heat-killed Staphylococcus aureus (S. aureus). Phagocytosis and production of hydrogen peroxide were simultaneously measured by flow cytometry using S. aureus labeled with propidium iodide and stained with 2,,7,-dichlorofluorescein diacetate. Eosinophils showed significantly lower activity than neutrophils in both phagocytosis and hydrogen peroxide production. Phagocytosis by both cells was decreased by heat-inactivated serum. Phagocytosis by neutrophils was significantly inhibited by CD16 mAb and CD32 mAb, whereas that by eosinophils was only inhibited by CD35 mAb. Whereas the mechanism of phagocytosis by neutrophils was mediated by CD16 and CD32, that of eosinophils was modulated by complement receptor 1 (CD35). [source] The effect of gender on the pharmacokinetics of verapamil and norverapamil in humanBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 7 2006S. Dadashzadeh Abstract The effects of gender on the pharmacokinetics of verapamil and its active metabolite, norverapamil, following single oral dose (80mg, Isoptin) to 12 healthy male (mean age: 25.75±2.42 years, mean body weight: 70.59±9.94kg) and 12 healthy female subjects (mean age: 24.08±2.84 years, mean body weight: 56.67±5.23kg) were investigated in the present study. Plasma concentrations of verapamil and norverapamil were analysed using a modified high-pressure liquid chromatography method. Pharmacokinetic parameters were calculated by non-compartmental analysis for each subject. For verapamil the half-life (t1/2) and mean residence time (MRT) were significantly shorter in women than men (p<0.01 and p<0.05, respectively). For other pharmacokinetic parameters of verapamil there were no significant differences between males and females. For norverapamil, t1/2, MRT and time to reach to the maximum plasma concentration (Tmax) showed statistically significant differences between the two genders. The AUC0,24 and AUC0,, ratios of norverapamil to verapamil were also calculated. The ratios were significantly higher in women compared with men. These observations indicate that the elimination rate of verapamil is faster in women than men which may be attributed to the higher activity of CYP3A4 or lower activity of P-glycoprotein in women compared with men. A contribution of both factors in the appearance of gender differences in verapamil pharmacokinetics is also possible. Copyright © 2006 John Wiley & Sons, Ltd. [source] Pharmacokinetics of nifedipine in TaiwaneseBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 2 2004Shu-Chen Chien Abstract To elucidate the pharmacokinetics of nifedipine in Taiwanese, a retrospective review of nifedipine bioequivalence studies completed in Taiwan in the past 5 years was conducted. A total of 198 healthy male volunteers were given a single dose of a 10 mg Adalat® capsule as a reference drug after overnight fasting. Pharmacokinetic parameters derived from Adalat® administration were calculated by non-compartmental analysis with the WinNonlin program. After oral administration of an immediate-release dosage form of a 10 mg nifedipine capsule to Taiwan residents, a skewed distribution with no clear evidence of bimodality of pharmacokinetic parameters was observed. The mean Cmax was 143.12±53.48 ng/ml, the mean AUC was 293.77±115.62 ng·h/ml, the mean T1/2 was 3.08±1.61 h, and the median value of Tmax was 0.61 h. Compared with other published studies, the Cmax and AUC of nifedipine after 10 mg administration were significantly higher in Taiwanese than in British and American subjects. However, the Cmax and AUC were similar to those of Indian and Mexican subjects. According to the antimode of AUC distribution of 22.5 ng·h/ml/mg proposed by Kleinbloesem, 69.7% of Taiwanese can be categorized as slow metabolizers. Based on the results in this study, the majority of Taiwanese show lower activity of nifedipine metabolism. Copyright © 2004 John Wiley & Sons, Ltd. [source] Kinetic limitations of a bioelectrochemical electrode using carbon nanotube-attached glucose oxidase for biofuel cellsBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009Xueyan Zhao Abstract Carbon nanotubes (CNTs) have been used for various bioelectrochemical applications, presumably for substantial improvement in performance. However, often only moderate results observed, with many governing factors have been considered and suggested yet without much systematic evaluation and verification. In this study, CNT-supported glucose oxidase (CNT,GOx) was examined in the presence of 1,4-benzoquinone (BQ). The intrinsic Michaelis parameters of the reaction catalyzed by CNT,GOx were found very close to those of native GOx. However, the Nafion entrapment of CNT,GOx for an electrode resulted in a much lower activity due to the limited availability of the embedded enzyme. Interestingly, kinetic studies revealed that the biofuel cell employing such an enzyme electrode only generated a power density equivalent to <40% of the reaction capability of the enzyme on electrode. It appeared to us that factors such as electron and proton transfer resistances can be more overwhelming than the heterogeneous reaction kinetics in limiting the power generation of such biofuel cells. Biotechnol. Bioeng. 2009; 104: 1068,1074. © 2009 Wiley Periodicals, Inc. [source] Antiproliferative effects of essential oils and their major constituents in human renal adenocarcinoma and amelanotic melanoma cellsCELL PROLIFERATION, Issue 6 2008M. R. Loizzo Materials and methods: Essential oils were obtained by hydrodistillation and were analysed by gas chromatography and gas chromatography coupled to mass spectrometry. Antiproliferative activity was tested on amelanotic melanoma C32 cells and on renal cell adenocarcinoma cells, using the sulphorhodamine B assay. Results: Cupressus sempervirens ssp. pyramidalis leaf oil exerted the highest cytotoxic activity with an IC50 value of 104.90 µg/mL against C32, followed by activity of P. orientalis and P. asperula on the renal adenocarcinoma cell line (IC50 of 121.93 and 139.17 µg/mL, respectively). P. orientalis essential oil was also active against amelanotic melanoma with an IC50 of 330.04 µg/mL. Three identified terpenes, linalool, ,-caryophyllene and ,-cedrol, were found to be active on both cell lines tested. Conclusions: Our findings provide novel insights into the field of cytotoxic properties of essential oils. This study provided evidence on how cytotoxic activity of the oils is not always related to their major constituents, except for lower activity found in both cell lines for ,-cedrol. Interestingly, ,-caryophyllene and linalool exhibited comparable IC50 values to the commercial drug vinblastine on the ACHN cell line. This opens a new field of investigation to discover mechanisms responsible for the observed activity. [source] A low-molecular mass ribonuclease from the brown oyster mushroomCHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2005L. Xia Abstract:, A ribonuclease, with a molecular mass of 9 kDa and an N-terminal sequence resembling the sequence of a fragment of tRNA/rRNA cytosine-C5-methylase and a fragment of a alanyl-tRNA synthetase, was isolated from fresh fruiting bodies of the brown oyster mushroom Pleurotus ostreatus. The ribonuclease was purified using a very simple protocol that comprised ion-exchange chromatography on carboxymethyl (CM)-cellulose and affinity chromatography on Affi-gel blue gel. Subsequent gel filtration by fast protein liquid chromatography on Superdex 75 and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis revealed that the ribonuclease was purified after the first two chromatographic steps. The ribonuclease was adsorbed on CM-cellulose and Affi-gel blue gel. The ribonuclease exhibited the highest activity toward poly A, lower activity toward poly C, slight activity toward poly G, and indiscernible activity toward poly U. The enzyme was stimulated upon exposure to 1 ,m Mg2+ and 10 ,m Zn2+, but was inhibited by the following ions at 10 mm: Ca2+, Mg2+, Zn2+, Cu2+, Fe2+, Mn2+, and Fe3+. The ribonuclease required a pH of 8.0 and a temperature of 50,70 °C to express maximal activity. It had a Km of 60 ,m toward yeast tRNA. It lacked mitogenic and HIV-1 reverse transcriptase inhibiting activities, but exerted antiproliferative activity toward leukemia L1210 cells. [source] C6-Unsubstituted Pyrazolo[3,4- d]pyrimidines Are Dual Src/Abl Inhibitors Effective against Imatinib Mesylate Resistant Chronic Myeloid Leukemia Cell LinesCHEMMEDCHEM, Issue 1 2009Maria Alessandra Santucci Dr. Abstract Docking simulations were used to predict the most favorable interaction between the T315I mutated form of Abl (invariably associated with resistance to the tyrosine kinase inhibitor imatinib mesylate, IM) and C6-unsubstituted and substituted pyrazolo[3,4- d]pyrimidines previously found to be dual Src/Abl inhibitors. Two C6-unsubstituted (1 and 2) and eight C6-substituted compounds (3,10) were selected and assayed for their effects on the Ba/F3 cell line transducing the wild-type p210Bcr,Abl construct, which is IM-sensitive, or three of the most common mutations associated with IM resistance in,vivo (T315I, Y253F, and E255K), and driven to drug resistance by saturating doses of IL-3 or by the expression of the Bcr,Abl construct coding for the p185 protein of acute lymphoblastic leukemia. Compounds 1 and 2 were active against all cell lines assayed (LD50 range: 0.7,4.3,,M), whereas C6-substituted compounds exhibited lower activity (LD50,8,,M for compound 3 toward the T315I mutant). Notably, 1 and 2 were also effective toward the T315I mutation, which is insensitive to dual Src/Abl inhibitors. The cytotoxic effects of 1 and 2 on IM-sensitive and IM-resistant Ba/F3 cells were attributable, at least in part, to their pro-apoptotic activity. Taken together, such findings suggest that C6-unsubstituted pyrazolo[3,4- d]pyrimidines may represent useful inhibitors to target IM-resistant chronic myeloid leukemia. [source] Conversion of Furfuryl Alcohol into Ethyl Levulinate using Solid Acid CatalystsCHEMSUSCHEM CHEMISTRY AND SUSTAINABILITY, ENERGY & MATERIALS, Issue 5 2009Jean-Paul Lange Dr. Abstract Cellulosic biofuel: Ethyl levulinate is a promising biofuel that can be obtained from lignocellulosic residues. A byproducts, furfural, can be converted into ethyl levulinate in an acid-based process. Here, the use of solid acid catalysts for the conversion of furfuryl alcohol into ethyl levulinate is reported. Furfural, a potential coproduct of levulinic acid, can be converted into levulinic acid via hydrogenation to furfuryl alcohol and subsequent ethanolysis to ethyl levulinate. The ethanolysis reaction is known to proceed in the presence of H2SO4. We show here that several strongly acidic resins are comparably effective catalysts for this reaction. Optimal performance is achieved by balancing the number of acid sites with their accessibility in the resin. Acidic zeolites such as H-ZSM-5 also catalyze this reaction, although with a lower activity and a higher coproduction of diethyl ether. [source] Association of angiotensin I-converting enzyme gene polymorphisms with aspirin intolerance in asthmaticsCLINICAL & EXPERIMENTAL ALLERGY, Issue 11 2008T-H. Kim Summary Background Aspirin-intolerant asthma (AIA) refers to the development of bronchoconstriction in asthmatic individuals following the ingestion of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs). Angiotensin I-converting enzyme (ACE), a membrane-bound peptidase present in the lung, plays a pivotal role in the metabolism of the endogenous peptides involved in the pathogenesis of asthma. Methods We screened a Korean asthma cohort (581 asthmatics including 81 aspirin-intolerant asthmatics and 231 aspirin-tolerant asthmatics, and 181 normal controls) for four single nucleotide polymorphisms (SNPs; ,262 A>T and ,115 T>C in the 5,-flanking region and +5467 T>C [Pro450Pro] and+11860 A>G [Thr776Thr] in the coding region) and one ins/del (+21288 CT) in the ACE gene. Results None of the SNPs or haplotypes showed any association with the development of asthma, but they were significantly associated with the risk of AIA. Logistic regression indicated that the frequency of the rare alleles of ,262 A>T and ,115 T>C was higher in subjects with AIA than in subjects with aspirin-tolerant asthma (ATA) (P=0.003,0.01, P corr=0.015,0.05). Subjects homozygous for the rare alleles of ,262 A>T and ,115 T>C showed a greater decline in forced expiratory volume in 1 s (FEV1) after aspirin provocation than those homozygous for the common alleles (P<0.05). A luciferase reporter assay indicated that ACE promoters containing the rare ,262 A>T allele possessed lower activity than did those containing the common allele (P=0.009). In addition, ACE promoters bearing the rare ,115 T>C allele had no luciferase activity. DNA,protein binding assays revealed a band containing the ACE promoter region (including ,262 A) and a protein complex. Conclusion The ,262 A>T polymorphism in the promoter of the ACE gene is associated with AIA, and the rare allele of ,262 A>T may confer aspirin hypersensitivity via the down-regulation of ACE expression. [source] | |||||||||||||||||||