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541.
Gang Wang Abiche H Dewilde Jianping Zhang Anoop Pal Malavika Vashist Dhimiter Bello Kenneth A Marx Susan J Braunhut Joel M Therrien 《Particle and fibre toxicology》2011,8(1):1-17
Background
There is growing evidence that exposure to small size particulate matter increases the risk of developing cardiovascular disease.Methods
We investigated plaque progression and vasodilatory function in apolipoprotein E knockout (ApoE -/-) mice exposed to TiO2. ApoE -/- mice were intratracheally instilled (0.5 mg/kg bodyweight) with rutile fine TiO2 (fTiO2, 288 nm), photocatalytic 92/8 anatase/rutile TiO2 (pTiO2, 12 nm), or rutile nano TiO2 (nTiO2, 21.6 nm) at 26 and 2 hours before measurement of vasodilatory function in aorta segments mounted in myographs. The progression of atherosclerotic plaques in aorta was assessed in mice exposed to nanosized TiO2 (0.5 mg/kg bodyweight) once a week for 4 weeks. We measured mRNA levels of Mcp-1, Mip-2, Vcam-1, Icam-1 and Vegf in lung tissue to assess pulmonary inflammation and vascular function. TiO2-induced alterations in nitric oxide (NO) production were assessed in human umbilical vein endothelial cells (HUVECs).Results
The exposure to nTiO2 was associated with a modest increase in plaque progression in aorta, whereas there were unaltered vasodilatory function and expression levels of Mcp-1, Mip-2, Vcam-1, Icam-1 and Vegf in lung tissue. The ApoE -/- mice exposed to fine and photocatalytic TiO2 had unaltered vasodilatory function and lung tissue inflammatory gene expression. The unaltered NO-dependent vasodilatory function was supported by observations in HUVECs where the NO production was only increased by exposure to nTiO2.Conclusion
Repeated exposure to nanosized TiO2 particles was associated with modest plaque progression in ApoE -/- mice. There were no associations between the pulmonary TiO2 exposure and inflammation or vasodilatory dysfunction. 相似文献542.
543.
Moncy V. Jose Sharon Marx Hironobu Murata Richard R. Koepsel Alan J. Russell 《Carbon》2012,50(11):4010-4020
A novel biosensor was prepared by immobilizing glucose oxidase on multi-walled carbon nanotube (MWCNT)-coated electrospun gold fibers. Homogeneous coating of the electrospun gold fibers by MWCNTs was achieved by electrophoretic deposition at 20 V (40 V cm?1), a deposition time of 30 s and a solution concentration of 0.25 mg mL?1. Scanning electron microscopy confirmed the complete coverage of MWCNTs on the fiber surface. The carboxylated MWCNTs on the gold fibers provided an anchor for covalent immobilization of glucose oxidase (GOX). GOX covalently coupled to conductive carbon nanotubes demonstrated direct electron transfer between the enzyme and the electrode surface without the need for a redox active mediator. Electrochemical characterization of the fabricated sensor by cyclic voltammetry revealed that the immobilized GOX exhibited a surface-confined reversible two-electron and two-proton reaction, with an electron transfer rate constant, ks, of 1.12 s?1 and a surface coverage of 1.1 × 10?12 mol cm?2. The sensor produced a linear response to glucose concentration up to 30.0 mM with a sensitivity of 0.47 μA mM?1 cm?2 and a detection limit of 4 μM. 相似文献
544.
Cramer J Rangam G Marx A Restle T 《Chembiochem : a European journal of chemical biology》2008,9(8):1243-1250
We report on comparative pre-steady-state kinetic analyses of exonuclease-deficient Escherichia coli DNA polymerase I (Klenow fragment, KF-) and the archaeal Y-family DinB homologue (Dbh) of Sulfolobus solfataricus. We used size-augmented sugar-modified thymidine-5'-triphosphate (T(R)TP) analogues to test the effects of steric constraints in the active sites of the polymerases. These nucleotides serve as models for study of DNA polymerases exhibiting both relatively high and low intrinsic selectivity. Substitution of a hydrogen atom at the 4'-position in the nucleotide analogue by a methyl group reduces the maximum rate of nucleotide incorporation by about 40-fold for KF- and about twelve fold for Dbh. Increasing the size to an ethyl group leads to a further twofold reduction in the rates of incorporation for both enzymes. Interestingly, the affinity of KF- for the modified nucleotides is only marginally affected, which would indicate no discrimination during the binding step. Dbh even has a higher affinity for the modified analogues than it does for the natural substrate. Misincorporation of either TTP or T(Me)TP opposite a G template causes a drastic decline in incorporation rates for both enzymes. At the same time, the binding affinities of KF- for these nucleotides drop by about 16- and fourfold, respectively, whereas Dbh shows only a twofold reduction. Available structural data for ternary complexes of relevant DNA polymerases indicate that both enzymes make close contacts with the sugar moiety of the dNTP. Thus, the varied proficiencies of the two enzymes in processing the size-augmented probes indicate varied flexibility of the enzymes' active sites and support the notion of active site tightness being a criterion for DNA polymerase selectivity. 相似文献
545.
Purpose
This study was designed to develop a novel technique called non-invasive keratograph dry-up time (NIK-DUT), which used an adapted corneal topographer, to analyse in-vitro contact lens surface dewetting and the effects of combinations of lenses and lens care solutions on dewetting.Methods
Variables were assessed to optimise sensitivity and reproducibility. To validate the method, in-vitro dewetting of silicone hydrogel contact lenses (balafilcon A, comfilcon A, lotrafilcon A, lotrafilcon B and senofilcon A) was tested. All lens types were soaked in OPTI-FREE® PureMoist® Multipurpose Disinfecting Solution (OFPM) and Sensitive Eyes® Saline Solution. The mean NIK-DUT, defined as drying of 25% of the placido ring measurement segments (NIK-DUT_S25), was calculated for each lens/lens solution combination and a visual map constructed representing the time and location of the dry-up event.Results
Optimal conditions for NIK-DUT measurement included mounting onto a glass stage with a surface geometry of r = 8.5 mm, e = 0, and measuring with high intensity red or white illumination. This method detected significant differences in contact lens dewetting with different lens soaking solutions. NIK-DUT_S25 for all lenses was longer when pre-soaked in OFPM versus saline. Visual analysis showed that dewetting of contact lenses was not uniform across surfaces and differed between test solutions.Conclusions
NIK-DUT is suitable for detecting differences in dewetting among various contact lenses and lens-care combinations. NIK-DUT can quantify the dewetting of large areas of lens surfaces with little subjective influence. Lens care solutions containing surface-active wetting agents were found to delay surface dewetting of silicone hydrogel lenses. 相似文献546.
Konrad Pfeilsticker und Friedhelm Marx 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1986,182(3):191-195
Summary A gaschromatographic/mass spectrometric method for separation and determination ofl-ascorbic acid (l-AA) and the different isomeric forms ofl-dehydro ascorbic acid (l-DAA) and 2,3-diketogulonic acid (l-DKG) in wheat doughs is described. Doughs with addedl-AA resp.l-DAA were included in the investigation. In all doughs thel-DAA was in its monomeric 3,6-anhydro-2-hydrate form. 2,3-DKG was not detectable.[/p]We confirm recent statements in the literature about the kinetics of the oxidation ofl-AA tol-DAA in doughs with addedl-AA. The loss of total ascorbic acid (l-AA+l-DAA) after dough making was approx. 30%. Only a small quantity ofl-AA was formed in doughs upon addition ofl-DAA. In this case the loss of total ascorbic acid was approx. 70%.[/p]From that and from investigations on doughs with 14C-labeledl-AA and measurements of the available thiol groups in doughs we conclude thatl-AA/l-DAA at least partially doesn't react like a redox system but thatl-DAA forms intermolecular condensation products with amino groups of proteins. These may contribute to improved baking quality.Zusammenfassung Es wird eine gaschromatographisch-massenspektrometrische Methode beschrieben, mit derl-Ascorbinsäure (l-AS) und die verschiedenen isomeren Formen derl-Dehydroascorbinsäure (l-DAS) und der 2,3-Diketogulonsdure (2,3-DKG) in Weizenmehlteigen getrennt und quantitativ bestimmt werden können. Teige mit Zusatz vonl-AS bzw.l-DAS wurden analysiert. Die L-DAS lag in allen Fällen in der monomeren bicyclischen 3,6-Anhydro-2-Hydrat-Form vor; 2,3-DKG war nicht nachweisbar. Bei Teigen mit Zusatz vonl-AS konnten die Angaben der Literatur über die Kinetik der Oxidation derl-AS zurl-DAS bestätigt werden. Der Verlust an Gesamtascorbinsäure (l-AS +l-DAS) lag nach dem Anteigen bei ca. 30%. In Teigen mit Zusatz vonl-DAS wurde nur wenigl-AS gebildet, der Verlust an Gesamtascorbinsäure lag in diesem Fall bei ca. 70%. Hieraus und aus Untersuchungen an Teigen mit 14C-markierterl-AS und Messungen des verfügbaren Thiolgehalts in Teigen schließen wir, dal-AS/l-DAS zumindest teilweise nicht als Redoxsystem reagiert, sondern daß diel-DAS mit Aminogruppen der Proteine intermolekulare Kondensationsprodukte bildet, die zur backverbessernden Wirkung beitragen dürften.[/p] 相似文献
547.
Ítala M.G. Marx Nuno Rodrigues Luís G. Dias Ana C.A. Veloso José A. Pereira Deisy A. Drunkler António M. Peres 《Food and Bioprocess Technology》2017,10(7):1310-1323
Table olives are prone to the appearance of sensory defects that decrease their quality and in some cases result in olives unsuitable for consumption. The evaluation of the type and intensity of the sensory negative attributes of table olives is recommended by the International Olive Council, although not being legally required for commercialization. However, the accomplishment of this task requires the training and implementation of sensory panels according to strict directives, turning out in a time-consuming and expensive procedure that involves a degree of subjectivity. In this work, an electronic tongue is proposed as a taste sensor device for evaluating the intensity of sensory defects of table olives. The potentiometric signal profiles gathered allowed establishing multiple linear regression models, based on the most informative subsets of signals (from 24 to 29 recorded during the analysis of olive aqueous pastes and brine solutions) selected using a simulated annealing meta-heuristic algorithm. The models enabled the prediction of the median intensities (R 2 ≥ 0.942 and RMSE ≤ 0.356, for leave-one-out or repeated K-fold cross-validation procedures) of butyric, musty, putrid, winey-vinegary, and zapateria negative sensations being, in general, the predicted intensities within the range of intensities perceived by the sensory panel. Indeed, based on the predicted mean intensities of the sensory defects, the electrochemical-chemometric approach developed could correctly classify 86.4% of the table olive samples according to their trade category based on a sensory panel evaluation and following the International Olive Council regulations (i.e., extra, 1st choice, 2nd choice, and olives that may not be sold as table olives). So, the satisfactory overall predictions achieved demonstrate that the electronic tongue could be a complementary tool for assessing table olive defects, reducing the effort of trained panelists and minimizing the risk of subjective evaluations. 相似文献
548.
Development of bioactive food packaging materials using immobilised bacteriocins lacticin 3147 and nisaplin 总被引:5,自引:0,他引:5
Scannell AG Hill C Ross RP Marx S Hartmeier W Elke Arendt K 《International journal of food microbiology》2000,60(2-3):241-249
Immobilisation of the bacteriocins nisin and lacticin 3147 to packaging materials was investigated. Stability of both cellulose-based bioactive inserts and anti-microbial polyethylene/polyamide pouches was examined over time. Anti-microbial activity against the indicator strain Lactococcus lactis subsp. lactis HP, in addition to Listeria innocua DPC 1770 and Staphylococcus aureus MMPR3 was observed for all bacteriocin-adsorbed materials. Activity retention of the inserts showed an initial decrease in the first week of storage but remained stable for the remaining 3 months of the trial. However, adsorption of lacticin 3147 to plastic film was unsuccessful, nisin bound well and the resulting film maintained its activity for 3-month period, both at room temperature and under refrigeration. When applied to food systems, the anti-microbial packaging reduced the population of lactic acid bacteria in sliced cheese and ham stored in modified atmosphere packaging (MAP) at refrigeration temperatures, thus extending the shelf life. Nisin-adsorbed bioactive inserts reduced levels of Listeria innocua by ≥2 log units in both products, and Staphylococcus aureus by 1.5 log units in cheese, and 2.8 log units in ham. Similar reductions were observed in cheese vacuum-packaged in nisin-adsorbed pouches. 相似文献
549.
Several concentrates with sodium bicarbonate (experimental) were compared with the same concentrates without sodium bicarbonate (control) throughout two lactations. During first lactation, two control concentrates were used in sequence in one comparison and three in another. Toward the end of first lactation, sodium bicarbonate was increased from 1.5 to 2.5% in concentrates, and that concentration was continued throughout the second lactation. During second lactation high-moisture corn with soybean meal was one concentrate; the other included half high-moisture barley and half dry corn and soybean meal. Fifty-two and 60 lactations of cows fed control and experimental rations contributed feed intake and production data. Ninety-four and 95 lactations of cows fed control or experimental rations contributed 305-day, mature-equivalent production data over three lactations. Inclusion of sodium bicarbonate in these rations had little effect on feed consumption, milk production, fat content of milk, efficiency of milk production, or change of body weight. The kind of concentrate did not alter the effect of sodium bicarbonate. Cows consuming control rations produced 8898 kg milk with 312 kg fat (305-day mature equivalent). Cows using bicarbonate produced 8972 kg milk with 312 kg fat. 相似文献
550.
André GordonBenjamin Schadow Clara E. QuijanoFriedhelm Marx 《Food research international (Ottawa, Ont.)》2011,44(7):2120-2127
The flora of Latin America attracts gaining interest as it provides a plethora of still unexplored or under-utilized fruits that can contribute to human well-being due to their nutritional value and their content of bioactive compounds. Clidemia rubra (Aubl.) Mart. is a shrub belonging to the family of the Melastomataceae that grows preferably in a tropical climate. This paper comprises a nutritional characterization of the berries from Clidemia rubra and provides data on the phenolic compounds as well as the antioxidant capacity of the fruit. Findings in macronutrients like protein, carbohydrates, and fat were comparable to that of common berry fruits. Clidemia rubra berries seemed to be a good source for dietary fibers and some minerals (Ca, Mn, and Zn). In contrast, contents of titratable acids and ascorbic acid were low. The polyphenolic profile was determined by using HPLC-MS/MS in comparison to standard compounds. Noteworthy amounts of cyanidin 3-O-rutinoside (39.43 ± 1.66 mg/100 g fresh weight (FW)), delphinidin 3-O-rutinoside (23.74 ± 1.18 mg/100 g FW), cyanidin 3-O-glucoside (11.68 ± 0.56 mg/100 g FW), and delphinidin 3-O-glucoside (6.08 ± 0.35 mg/100 g FW) were found. Non-anthocyanin phenolic constituents were phenolic acids (gallic, protocatechuic, p-hydroxy-benzoic, vanillic, and caffeic acid), flavan-3-ols (epigallocatechin, epigallocatechin gallate, and epicatechin gallate), and 11 different myricetin and quercetin derivatives of which quercetin 3-O-arabinoside (5.26 ± 0.16 mg/100 g FW) and quercetin 3-O-rhamnoside (5.06 ± 0.08 mg/100 g FW) were dominating. Anthocyanins and ascorbic acid were mainly responsible for the antioxidant capacity of Clidemia rubra berries assessed with the total oxidant scavenging capacity (TOSC) assay. 相似文献