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Publication
Journal: ACS Nano
November/6/2012
Abstract
The adsorption of polypeptides containing an N-terminal tryptophan (Trp) residue attached to a hexa-backbone of alanine, serine, lysine, histidine, and aspartate was investigated by monitoring the fluorescence response of the Trp chromophore upon titration with metal oxide nanoparticles (MOx-NPs: CuO, Co(3)O(4), TiO(2), MgO, and CeO(2)). After correction for light-scattering effects, a strong static fluorescence quenching was observed upon addition of CuO and Co(3)O(4) to the peptides. The interaction of MOx-NPs with the peptides was assigned to an adsorption of the peptide backbone on the nanoparticle surface. The method was refined using a derivatized amino acid, 5-fluoro-Trp (5F-Trp), which resulted in a stronger fluorescence response. The use of the fluorescent amino acid labels allowed the direct assessment of the adsorption propensities of Trp-containing peptides in dependence on the backbone, which was verified by zeta-potential measurements. Moreover, upon addition of different analytes to nanoparticles with preadsorbed Trp-containing polypeptides, adsorption propensities of the analytes were assessed by an indicator displacement strategy; that is, addition of increasing amounts of analyte resulted in a continuous fluorescence enhancement/recovery. This method afforded adsorption propensities for several analytes. The relative binding constants for the MOx-NPs, obtained from the competitive titrations, varied by more than 6 orders of magnitude for CuO (5F-TrpHis(6)-NH(2)>> TrpAsp(6)-NH(2), TrpSer(6)-NH(2)>> TrpLys(6)-NH(2), Trp, 5F-Trp>> TrpAla(6)-NH(2)) but only 4 for Co(3)O(4) (TrpHis(6)-NH(2), TrpAsp(6)-NH(2) ≫ TrpLys(6)-NH(2), TrpAla(6)-NH(2), TrpSer(6)-NH(2), Trp, 5F-Trp). The study reveals that MOx-NPs adsorb biomolecular analytes with high selectivity, which has immediate implications for their applications in protein purification, drug delivery, and, potentially, for the assessment of their toxicology.
Publication
Journal: Nanotechnology
June/15/2009
Abstract
Rabbit-immunoglobulin antibodies (r-IgGs) and bovine serum albumin (BSA) have been immobilized onto sol-gel-derived nanostructured cerium oxide (nanoCeO(2)) film fabricated onto an indium-tin-oxide (ITO) coated glass plate to detect ochratoxin-A (OTA). Broad reflection planes obtained in x-ray diffraction (XRD) patterns reveal the formation of CeO(2) nanostructures. Electrochemical studies reveal that nanoCeO(2) particles provide an increased electroactive surface area for loading of r-IgGs with desired orientation, resulting in enhanced electron communication between r-IgGs and electrode. BSA/r-IgGs/nano CeO(2)/ITO immunoelectrode exhibits improved characteristics such as linear range (0.5-6 ng dl(-1)), low detection limit (0.25 ng dl(-1)), fast response time (30 s) and high sensitivity (1.27 microA ng(-1) dl(-1) cm(-2)). The high value of the association constant (K(a), 0.9 x 10(11) l mol(-1)) indicates the high affinity of the BSA/r-IgGs/nanoCeO(2)/ITO immunoelectrode to OTA.
Publication
Journal: Molecular Reproduction and Development
February/8/2007
Abstract
In this study we have examined the meiosis-inducing influence of adenosine analogs in mouse oocytes. When a varied group of nucleosides and nucleotides were tested on overnight cultures of hypoxanthine-arrested, cumulus cell-enclosed oocytes (CEO), halogenated adenosine nucleosides, but not native adenosine, exhibited a significant meiosis-inducing capability. When tested under a variety of conditions, meiotic induction by 8-bromo-adenosine (8-Br-Ado) and a second adenosine analog, methylmercaptopurine riboside (MMPR), was especially potent in denuded oocytes (DO) compared to CEO and was not dependent on the type of inhibitor chosen to maintain meiotic arrest. Germinal vesicle breakdown (GVB) was stimulated with rapid kinetics and was preceded by an increase in AMP-activated protein kinase (AMPK) activity. Moreover, compound C, an inhibitor of AMPK, blocked the meiosis-inducing activities of both adenosine analogs. When tested for an effect on meiotic progression to metaphase II (MII) in spontaneously maturing CEO, 8-Br-Ado and the AMPK activator, 5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside (AICAR), increased the percentage of MII-stage oocytes, but MMPR decreased this number. Adenosine and inhibitors of de novo purine synthesis had no effect on the completion of maturation, while compound C suppressed this process. These results support the proposition that oocyte AMPK mediates the positive influence of AICAR and 8-Br-Ado on both the initiation and completion of meiotic maturation. The role of AMPK in MMPR action is less clear.
Publication
Journal: Molecular and Cellular Endocrinology
July/20/2006
Abstract
Meiosis activating sterol (MAS) have been found to be able to promote oocytes meiotic maturation of small animals in vitro, such as mouse, rat and rabbit. But in large animals, whether MAS play the same function, especially the physiological mechanisms of MAS on oocytes maturation are not clear. To our knowledge, this is the first time to investigate the role and signal pathway of MAS on FSH-induced porcine oocytes meiotic resumption. Porcine cumulus-enclosed oocytes (CEOs) isolated from 3 to 5mm follicles were cultured in the FSH-medium for 24h supplemented with 0-50 microM RS21745 or 0-100 microM RS21607 (two specific inhibitors of lanosterol 14alpha-demethylase that converts lanosterol to FF-MAS), or cultured in FSH-medium with 25 microM RS21745 for 0-24h firstly, then transferred into a new FSH-medium (the total culture time is 24h). The results revealed that RS21745 or RS21607 could inhibit FSH-induced porcine CEOs meiotic resumption in a dose and time-dependent manner. Meanwhile, FSH-induced cumulus expansion could also be inhibited dose-dependently by RS21745 or RS21607. Otherwise, AY9944-A-7, an inhibitor of Delta14-reductase which promotes cholesterol accumulation from FF-MAS, had no effect on both denuded oocytes (DOs) cultured for 24 or 44 h and CEOs cultured for 24h meiotic resumption, but it could promote CEOs meiotic resumption after 44 h culture. In addition, we got that 10(-8) to 10(-6)M PMA, an activator of PKC pathway, could reverse the inhibiting effect of RS21745 on FSH-induced CEOs meiotic resumption and enhance the rate of germinal vesicle breakdown (GVBD) of CEOs cultured in medium with hypoxanthine (HX). Moreover, 5-10 microM chelerythrine chloride, an inhibitor of PKC, could enhance the inhibitory effect of RS21745 on FSH-induced porcine oocytes resumption of meiosis. All the data of this study support that endogenous FF-MAS takes part in the FSH-induced porcine oocytes meiotic resumption and might play an active role via PKC signal pathway.
Publication
Journal: Virus Genes
August/14/2012
Abstract
This study was conducted to identify unique nucleotide differences in two U.S. chicken embryo origin (CEO) vaccines [LT Blen (GenBank accession: JQ083493) designated as vaccine 1; Laryngo-Vac(®) (GenBank accession: JQ083494) designated as vaccine 2] of infectious laryngotracheitis virus (ILTV) genomes compared to an Australian Serva vaccine reference ILTV genome sequence [Gallid herpesvirus 1 (GaHV-1); GenBank accession number: HQ630064]. Genomes of the two vaccine ILTV strains were sequenced using Illumina Genome Analyzer 2X of 36 cycles of single-end reads. Results revealed that few nucleotide differences (23 in vaccine 1; 31 in vaccine 2) were found and indicate that the US CEO strains are practically identical to the Australian Serva CEO strain, which is a European-origin vaccine. The sequence differences demonstrated the spectrum of variability among vaccine strains. Only eight amino acid differences were found in ILTV proteins including UL54, UL27, UL28, UL20, UL1, ICP4, and US8 in vaccine 1. Similarly, in vaccine 2, eight amino acid differences were found in UL54, UL27, UL28, UL36, UL1, ICP4, US10, and US8. Further comparison of US CEO vaccines to several ILTV genome sequences revealed that US CEO vaccines are genetically close to both the Serva vaccine and 63140/C/08/BR (GenBank accession: HM188407) and are distinct from the two Australian-origin CEO vaccines, SA2 (GenBank accession: JN596962) and A20 (GenBank accession: JN596963), which showed close similarity to each other. These data demonstrate the potential of high-throughput sequencing technology to yield insight into the sequence variation of different ILTV strains. This information can be used to discriminate between vaccine ILTV strains and further, to identify newly emerging mutant strains of field isolates.
Publication
Journal: Journal of Agricultural and Food Chemistry
December/30/2013
Abstract
Studies have shown that CeO₂ nanoparticles (NPs) can be accumulated in plants without modification, which could pose a threat for human health. In this research, cilantro (Coriandrum sativum L.) plants were germinated and grown for 30 days in soil amended with 0 to 500 mg kg⁻¹ CeO₂ NPs and analyzed by spectroscopic techniques and biochemical assays. At 125 mg kg⁻¹, plants produced longer roots (p ≤ 0.05), and at 500 mg kg⁻¹, there was higher Ce accumulation in tissues (p ≤ 0.05). At 125 mg, catalase activity significantly increased in shoots and ascorbate peroxidase in roots (p ≤ 0.05). The FTIR analyses revealed that at 125 mg kg⁻¹ the CeO₂ NPs changed the chemical environment of carbohydrates in cilantro shoots, for which changes in the area of the stretching frequencies were observed. This suggests that the CeO₂ NPs could change the nutritional properties of cilantro.
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Publication
Journal: Molecular and Cellular Endocrinology
February/8/2005
Abstract
Nitric oxide (NO) has been recently shown to act with a dual action in mouse oocyte meiotic maturation depending on its concentration, but the mechanism(s) through which it influences oocyte maturation has not been fully clarified to date. The purpose of this study was to test the hypothesis that different signaling mechanisms exist for NO-stimulated and NO-inhibited in vitro maturation of meiosis in cumulus cell-enclosed oocytes (CEOs) from PMSG-primed immature female mice. CEOs were cultured in both spontaneous maturation model and hypoxanthine (HX) arrested model to investigate the mechanism(s). Sodium nitroprusside (SNP, an NO donor) at a concentration of 1mM delayed significantly germinal vesical breakdown (GVBD) during the first 5 h of incubation period and further inhibited the formation of first polar body (PB1) at the end of 24 h of incubation. While SNP, at a concentration of 10 microM, stimulated significantly the meiotic maturation of oocytes by overcoming the inhibition of HX. Methinine blue (MB, 10 microM) or 1-H-[1,2,4] oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ, 10 microM)), two soluble guanylate cyclase (sGC) inhibitors, could reverse SNP-inhibited spontaneous oocyte maturation, but had no effect on SNP-stimulated meiotic maturation in the presence of HX. 8-Br-cGMP (1mM), a cell-permeating cGMP analogue, demonstrated a significant inhibitory effect on both spontaneous meiotic maturation and HX-arrested meiotic maturation. The delay effect of SNP on GVBD occurrence was similar to that of forskolin (6 microM, an adenylate cyclase stimulator) and rolipram (250 microM, a phosphodiesterase 4 inhibitor), two cAMP elevating reagents. Both forskolin and rolipram reversed significantly the SNP-stimulated meiotic maturation, but did not reverse the SNP-inhibited spontaneous meiotic maturation. Cilostamide (1 microM), the selective inhibitor of phosphodiestrase 3 (PDE3), could mimic the inhibitory effect of HX on the spontaneous meiotic maturation in CEOs and this inhibitory effect could also be reversed by SNP (10 microM). Moreover, sphingosine (3 microM), a protein kinase C (PKC) inhibitor, blocked the SNP-inhibited spontaneous meiotic maturation, but did not block the SNP-stimulated meiotic maturation. Clearly, these results suggest that pathway differences are present between SNP-inhibited spontaneous meiotic maturation and SNP-stimulated meiotic maturation of mouse oocytes.
Publication
Journal: Journal of Colloid and Interface Science
October/17/2010
Abstract
Recent studies have shown that nano-bio interfaces are the most complex and the least understood. Notably, nanotoxicity of these nanoparticles is not even well recognized. In this work, we examined the toxic effects of different nanoparticles on bacteria cells (Nitrosomonas europaea). The four nanoparticles involved are: 25 nm anatase TiO(2), 200 nm anatase TiO(2), ZnO and CeO(2) particles. These particles will have different electrical charges in the cell cultivating media. It has been observed that even with only 4 h of dosing, all of the particles caused apparent morphological damage to the cells. Experimental results suggest that ZnO particles exert the stress on cells by its dissolution and releasing of Zn(2+) ions. The TEM and AUC (analytical ultracentrifuge) result suggest that cells become heavier in presence of CeO(2) and TiO(2) particles. No visible clear intrusions of bulk nanoparticles were observed. However, both the analytical ultracentrifuge and TEM results show that cells are heavier when being damaged.
Publication
Journal: Domestic Animal Endocrinology
August/7/2008
Abstract
Previous studies have shown that epidermal growth factor (EGF) has the ability to promote in vitro cultured porcine oocyte maturation. However, little is known about the detailed downstream events in EGF-induced meiotic resumption. We designed this study to determine the relationship of EGF, EGFR, phosphatidylinositol 3-kinase (PI3-kinase), MAPK, and germinal vesicle breakdown (GVBD) during oocyte maturation. Our results showed that GVBD in cumulus-enclosed oocytes (CEOs) but not in denuded oocytes (DOs) was induced by EGF in a dose-dependent manner, which indicated that cumulus cells but not oocyte itself were the main target for EGF-induced meiotic resumption. Furthermore, we found that MAPK in cumulus cells rather than in oocyte was activated immediately after EGF administration. To explore whether EGF exerts its functions through MAPK pathway, the activities of EGF receptor (EGFR) and MAPK were inhibited by employing AG1478 and U0126, respectively. Inhibition of MAPK blocked EGF-induced GVBD, whereas inhibition of EGFR prevented MAPK activation. Both AG1478 and U0126 could lead to the failure of EGF-induced GVBD singly. Notably, we found that LY294002, a specific inhibitor of PI3-kinase, effectively inhibited EGF-induced MAPK activation as well as subsequent oocyte meiotic resumption and this inhibition could not be reversed by adding additional EGF. Thus, PI3-kinase-induced MAPK activation in cumulus cells mediated EGF-induced meiotic resumption in porcine CEOs. Together, this study provides evidences demonstrating a linear relationship of EGF/EGFR, PI3-kinase, MAPK and GVBD and presents a relatively definitive mechanism of EGF-induced meiotic resumption of porcine oocyte.
Publication
Journal: Journal of the American Chemical Society
June/30/2009
Abstract
Electron paramagnetic resonance (EPR) spectroscopy and spin trapping were used to explore the mechanism of alcohol oxidation over gold catalysts. Reaction of secondary alcohols with supported and unsupported gold catalysts (e.g., Au/CeO(2), polymer-incarcerated Au nanoparticles, PPh(3)-protected Au nanoparticles) in the presence of spin traps led to the formation of a hydrogen spin adduct. Using isotope labeling, we confirmed that the hydrogen in the spin adduct originates from the cleavage of the C-H bond in the alcohol molecule. The formation of the hydrogen spin adduct most likely results from the abstraction of hydrogen from the Au surface by a spin trap. These results thus strongly suggest intermediate formation of Au-H species during alcohol oxidation. The role of oxygen in this mechanism is to restore the catalytic activity rather than oxidize alcohol. This was further confirmed by carrying out gold-catalyzed alcohol oxidation in the absence of oxygen, with nitroxides as hydrogen abstractors. The support (e.g., metal oxides) can activate oxygen and act as an H abstractor from the gold surface and hence lead to a faster recovery of the activity. Peroxyl radicals were also observed during alcohol oxidation, consistent with a free-radical autoxidation mechanism. However, this mechanism is likely to be a minor side reaction, which does not lead to the formation of an appreciable amount of oxidation products.
Publication
Journal: Research in Pharmaceutical Sciences
January/23/2014
Abstract
Carum carvi L. (Apiaceae family) or caraway is a common household plant grown around the world including Iran. Caraway fruits are used as flavoring agent in foods and beverages, and have various traditional uses in ethnomedicine. Anti-inflammatory, spasmolytic, antimicrobial, antioxidant, carminative and immunomodulatory properties of caraway suggest that it might exert beneficial effects on inflammatory bowel disease (IBD). Therefore, this study was carried out to investigate the effects of caraway hydroalcoholic extract (CHE) and its essential oil (CEO) in an immunological model of colitis in rats induced by trinitrobenzene sulfonic acid (TNBS). Different doses of CHE (100, 200, 400 mg/kg) and CEO (100, 200, 400 μl/kg) were administered orally (p.o.) and also doses of CHE (100, 400 mg/kg) and CEO (100, 400 μl/kg) were given intraperitoneally (i.p.) to the separate groups of male Wistar rats (n=6). Administration of the doses started 6 h after induction of colitis and continued daily for 5 consecutive days. Wet colon weight/length ratio was measured and tissue damage scores as well as indices of colitis were evaluated both macroscopically and histopathologically. CHE and CEO at all doses tested were effective in reducing colon tissue lesions and colitis indices and the efficacy was nearly the same when different doses of plant fractions were administered p.o. or i.p. Administration of prednisolone (p.o., 4 mg/kg), Asacol® (mesalazine microgranules, p.o., 100 mg/kg) and hydrocortisone acetate (i.p., 20 mg/kg) as references were effective in reducing colon tissue injures as well. These data suggest that caraway fractions are both effective and possess anti-colitic activity irrespective of the dose and route of administration.
Publication
Journal: Journal of Physics Condensed Matter
July/31/2011
Abstract
In the last two decades the atomic force microscope (AFM) has become the premier tool for topographical analysis of surface structures at the nanometre scale. In its ultimately sensitive implementation, namely dynamic scanning force microscopy (SFM) operated in the so-called non-contact mode (NC-AFM), this technique yields genuine atomic resolution and offers a unique tool for real space atomic-scale studies of surfaces, nanoparticles as well as thin films, single atoms and molecules on surfaces irrespective of the substrate being electrically conducting or non-conducting. Recent advances in NC-AFM have paved the way for groundbreaking atomic level insight into insulator surfaces, specifically in the most important field of metal oxides. NC-AFM imaging now strongly contributes to our understanding of the surface structure, chemical composition, defects, polarity and reactivity of metal oxide surfaces and related physical and chemical surface processes. Here we review the latest advancements in the field of NC-AFM applied to the fundamental atomic resolution studies of clean single crystal metal oxide surfaces with special focus on the representative materials Al(2)O(3)(0001), TiO(2)(110), ZnO(1000) and CeO(2)(111).
Publication
Journal: Carbohydrate Polymers
October/27/2016
Abstract
This work is dedicated to prepare liposomal dry powder formulations of inclusion complexes of clove essential oil (CEO) and its main component eugenol (Eug). Ethanol injection method and membrane contactor were applied to prepare liposomes at laboratory and large scale, respectively. Various liposomal formulations were tested: (1) free hydroxypropyl-β-cyclodextrin loaded liposomes; (2) drug in hydroxypropyl-β-cyclodextrin in liposomes (DCL); (3) DCL2 obtained by double loading technique, where the drug is added in the organic phase and the inclusion complex in the aqueous phase. Liposomes were characterized for their particle size, polydispersity index, Zeta potential, morphology, encapsulation efficiency of CEO components and Eug loading rate. Reproducible results were obtained with both injection devices. Compared to Eug-loaded liposomes, DCL and DCL2 improved the loading rate of Eug and possessed smaller vesicles size. The DPPH(•) scavenging activity of Eug and CEO was maintained upon incorporation of Eug and CEO into DCL and DCL2. Contrary to DCL2, DCL formulations were stable after 1 month of storage at 4°C and upon reconstitution of the dried lyophilized cakes. Hence, DCL in aqueous and lyophilized forms, are considered as a promising carrier system to preserve volatile and hydrophobic drugs enlarging their application in cosmetic, pharmaceutical and food industries.
Publication
Journal: Journal of Hazardous Materials
October/24/2012
Abstract
Little is known about the fate, transport, and bioavailability of CeO(2) nanoparticles (NPs) in soil. Moreover, there are no reports on the effect of surface coating upon NPs uptake by plants. In this study, Zea mays plants were grown for one month in unenriched and organic soils treated with coated and uncoated CeO(2) NPs. In addition, plants were exposed to fluorescein isothiocyanate (FITC)-stained CeO(2) NPs and analyzed in a confocal microscope. In organic soil, roots from uncoated and coated NPs at 100, 200, 400, and 800mg kg(-1) had 40, 80, 130, and 260% and 10, 70, 90, and 40% more Ce, respectively, compared to roots from unenriched soil. Conversely, shoots of plants from unenriched soil had significantly more Ce compared with shoots from organic soil. Confocal fluorescence images showed FITC-stained CeO(2) NP aggregates in cell walls of epidermis and cortex, suggesting apoplastic pathway. The μXRF results revealed the presence of CeO(2) NP aggregates within vascular tissues. To the authors knowledge this is the first report on the effects of surface coating and organic matter on Ce uptake from CeO(2) NPs and upon the mechanisms of CeO(2) NPs uptake by higher plants.
Publication
Journal: Human Reproduction
September/29/2018
Abstract
Can a discriminant threshold be determined for human sperm DNA oxidation?
A discriminant threshold was found with 65.8% of 8-hydroxy-2'-deoxyguanosine (8-OHdG)-positive sperm cells and a mean intensity of fluorescence (MIF) of 552 arbitrary units.
Oxidative stress is known to interfere with sperm quality and fertilizing capacity. However, current practice does not include the routine determination of oxidative DNA damage in spermatozoa; optimized consensus protocols are lacking and no thresholds of normality have been established.
Intra- and inter-method comparisons between four protocols (I-IV) were conducted to determine the most relevant and efficient means of assessing human sperm 8-OHdG content. Tests of assay repeatability, specificity, sensitivity and stability were performed to validate an optimized methodology for routine diagnostic use.
This prospective study compared three immuno-detection methods including immunocytochemistry, fluorescence microscopy and flow cytometry. Sperm DNA oxidation for 80 patients was determined relative to semen parameters and clinical conditions, using the selected immuno-detection protocol in comparison with a commercial kit. These patients (age 35 ± 1 years: mean ± SEM) presented with normozoospermic (n = 40) or altered parameters (necro- or/and astheno- or/and teratozoospermia or/and leukocytospermia).
Significant positive Pearson and Spearman correlations were determined for 8-OHdG values and sperm parameters using protocol III. A notable high and positive correlation was revealed for MIF with BMI and leukocyte concentration. Protocol III was the most discriminating method regarding assay repeatability, specificity, sensitivity, stability and reliability for sperm parameter alterations, in particular leukocytospermia according to parametric or non-parametric tests, effect-size determinations and factorial analysis such as principal component analysis and factor discriminant analysis. Of interest is that 39% of the subjects with 'pathological' sperm DNA oxidation values were normozoospermic.
The oligozoospermic population was not evaluated in this study because insufficient material was available to carry out the comparisons. However, spermatozoa concentration was taken into account in the statistical analysis.
Our study is the first validation of a protocol to determine a discriminant threshold for human sperm DNA oxidation. The protocol's detection accuracy for 8-OHdG human sperm DNA residues, stability over time, and relationship to human sperm quality were demonstrated. The assay should find application in the diagnosis of male factor infertility associated with oxidative stress.
This work was funded by institutional grants from the CNRS, INSERM and Université Clermont Auvergne (to J.R.D.) and by Clermont-Ferrand Hospital-CECOS research funds (to L.J. and F.B.). P.G., A.M., R.J.A. and J.D. are, respectively, CEO, scientific director and scientific advisors of a US-based biotech company (Celloxess, Princeton, NJ, USA) involved in preventative medicine with a focus on the generation of antioxidant oral supplements.
Publication
Journal: Journal of Hazardous Materials
April/24/2013
Abstract
Cerium oxide (CeO(2)) and zinc oxide (ZnO) nanoparticles (NPs) are extensively used in a variety of instruments and consumer goods. These NPs are of great concern because of potential toxicity towards human health and the environment. The present work aimed to assess the toxic effects of 10nm CeO(2) and ZnO NPs towards the nitrogen fixing bacterium Sinorhizobium meliloti. Toxicological parameters evaluated included UV/Vis measurement of minimum inhibitory concentration, disk diffusion tests, and dynamic growth. Ultra high-resolution scanning transmission electron microscopy (STEM) and infrared spectroscopy (FTIR) were utilized to determine the spatial distribution of NPs and macromolecule changes in bacterial cells, respectively. Results indicate that ZnO NPs were more toxic than CeO(2) NPs in terms of inhibition of dynamic growth and viable cells counts. STEM images revealed that CeO(2) and ZnO NPs were found on bacterial cell surfaces and ZnO NPs were internalized into the periplasmic space of the cells. FTIR spectra showed changes in protein and polysaccharide structures of extra cellular polymeric substances present in bacterial cell walls treated with both NPs. The growth data showed that CeO(2) NPs have a bacteriostatic effect, whereas ZnO NPs is bactericidal to S. meliloti. Overall, ZnO NPs were found to be more toxic than CeO(2) NPs.
Publication
Journal: Journal of Agricultural and Food Chemistry
October/14/2014
Abstract
There is lack of information about the effects of nanoparticles (NPs) on cucumber fruit quality. This study aimed to determine possible impacts on carbohydrates, proteins, mineral nutrients, and antioxidants in the fruit of cucumber plants grown in soil treated with CeO2 and ZnO NPs at 400 and 800 mg/kg. Fourier transform infrared spectroscopy (FTIR) was used to detect changes in functional groups, while ICP-OES and μ-XRF were used to quantify and map the distribution of nutrient elements, respectively. Results showed that none of the ZnO NP concentrations affected sugars; however at 400 mg/kg, CeO2 and ZnO NPs increased starch content. Conversely, CeO2 NPs did not affect starch content but impacted nonreducing sugar content (sucrose). FTIR data showed changes in the fingerprint regions of 1106, 1083, 1153, and 1181, indicating that both NPs altered the carbohydrate pattern. ZnO NPs did not impact protein fractionation; however, CeO2 NPs at 400 mg/kg increased globulin and decreased glutelin. Both CeO2 and ZnO NPs had no impact on flavonoid content, although CeO2 NPs at 800 mg/kg significantly reduced phenolic content. ICP-OES results showed that none of the treatments reduced macronutrients in fruit. In case of micronutrients, all treatments reduced Mo concentration, and at 400 mg/kg, ZnO NPs reduced Cu accumulation. μ-XRF revealed that Cu, Mn, and Zn were mainly accumulated in cucumber seeds. To the best of the authors' knowledge this is the first report on the nutritional quality of cucumber fruit attributed to the impact of CeO2 and ZnO NPs.
Publication
Journal: Environmental Science & Technology
February/9/2011
Abstract
CeO(2)/TiO(2) and CeO(2)-WO(3)/TiO(2) catalysts prepared by impregnation method assisted with ultrasonic energy were investigated on the selective catalytic reduction (SCR) of NO(x) (NO and NO(2)) by NH(3). The catalytic activity of 10% CeO(2)/TiO(2) (CeTi) was greatly enhanced by the addition of 6% WO(3) in the broad temperature range of 200-500 °C, the promotion mechanism was proposed on basis of the results of in situ diffuse reflectance infrared transform spectroscopy (DRIFT). When NH(3) was introduced into both catalysts preadsorbed with NO + O(2), SCR would not proceed except for the reaction between NO(2) and ammonia. For CeO(2)/TiO(2) catalysts, coordinated NH(3) linked to Lewis acid sites were the main adsorbed ammonia species. When NO + O(2) was introduced, all the ammonia species consumed rapidly, indicating that these species could react with NO(x) effectively. Two different reaction routes, L-H mechanism at low temperature (<200 °C) and E-R mechanism at high temperatures (>200 °C), were presented for SCR reaction over CeO(2)/TiO(2) catalyst. For CeO(2)-WO(3)/TiO(2) catalysts, the Lewis acid sites on Ce(4+) state could be converted to Brønsted acid sites due to the unsaturated coordination of Ce(n+) and W(n+) ions. When NO + O(2) was introduced, the reaction proceeded more quickly than that on CeO(2)/TiO(2). The reaction route mainly followed E-R mechanism in the temperature range investigated (150-350 °C) over CeO(2)-WO(3)/TiO(2) catalysts. Tungstation was beneficial for the formation of Ce(3+), which would influence the active sites of the catalyst and further change the mechanisms of SCR reaction. In this way, the cooperation of tungstation and the presence of Ce(3+) state resulted in the better activity of CeO(2)-WO(3)/TiO(2) compared to that of CeO(2)/TiO(2).
Publication
Journal: BMC Health Services Research
August/21/2017
Abstract
Decreasing hospital length of stay, and so freeing up hospital beds, represents an important cost saving which is often used in economic evaluations. The savings need to be accurately quantified in order to make optimal health care resource allocation decisions. Traditionally the accounting cost of a bed is used. We argue instead that the economic cost of a bed day is the better value for making resource decisions, and we describe our valuation method and estimations for costing this important resource.
We performed a contingent valuation using 37 Australian Chief Executive Officers' (CEOs) willingness to pay (WTP) to release bed days in their hospitals, both generally and using specific cases. We provide a succinct thematic analysis from qualitative interviews post survey completion, which provide insight into the decision making process.
On average CEOs are willing to pay a marginal rate of $216 for a ward bed day and $436 for an Intensive Care Unit (ICU) bed day, with estimates of uncertainty being greater for ICU beds. These estimates are significantly lower (four times for ward beds and seven times for ICU beds) than the traditional accounting costs often used. Key themes to emerge from the interviews include the importance of national funding and targets, and their associated incentive structures, as well as the aversion to discuss bed days as an economic resource.
This study highlights the importance for valuing bed days as an economic resource to inform cost effectiveness models and thus improve hospital decision making and resource allocation. Significantly under or over valuing the resource is very likely to result in sub-optimal decision making. We discuss the importance of recognising the opportunity costs of this resource and highlight areas for future research.
Publication
Journal: Hospital Topics
June/26/2006
Abstract
The purpose of this study is to evaluate empirically in the hospital administrative environment the relationship of leadership behaviors to subordinate manager's perceived outcomes, through examination of B. M. Bass's (1985) model of transformational, transactional, and laissez-faire leadership. The author measured leadership orientation and outcome factors through subordinate managers' ratings of hospital CEOs using a questionnaire, which asked: Is there a relationship between the leadership styles of hospital CEOs and subordinate managers' self-reported willingness to exert extra effort, perception of leader effectiveness and satisfaction with their leader? Findings revealed that the relationship between transformational leadership and the outcome factors were stronger and more positive than were the transactional and laissez-faire styles. These findings are consistent with the hierarchal patterns reported and support the universality of the model.
Publication
Journal: Journal of General Internal Medicine
November/24/1996
Abstract
To determine health care leaders' opinions about a prominent guide to hospital quality, we surveyed 82 chief executive officers (CEOs) and 80 chiefs of staff of hospitals listed in the 1994 edition of the guide and 50 directors of employer based coalitions. Most of the CEOs (87%) and chiefs of staff (86%) said the guide was used in advertising. More than three quarters of the CEOs, chiefs of staff, and coalition directors who were familiar with the guide thought it was accurate, and most indicated that key constituencies (e.g., physicians, corporate managers) were aware of the guide. Our results demonstrate the likely influence of one prominent guide to health care quality and highlight the need for formal independent assessment of such guides.
Publication
Journal: Advanced Materials
March/23/2011
Publication
Journal: BMC Health Services Research
January/12/2011
Abstract
BACKGROUND
This study focused on the manager role in the manager-physician relationship, considered from the manager perspective. The aim was to understand how top executives in Swedish healthcare regard management of physicians in their organisations, and what this implies for the manager role in relation to the medical profession. Abbott's theory of professional jurisdiction was used to inform thinking about managerial control and legitimacy in relation to physicians.
METHODS
Data from semi-structured individual interviews with 18 of the 20 county council chief executive officers (CEOs) in Sweden were subjected to qualitative analysis.
RESULTS
The results show that, when asked about their views on management of physicians, the CEOs talked about "how physicians are" rather than describing their own or their subordinate managers' managerial behaviour or strategies. Three types of descriptions of physicians were identified: 1) they have high status and expertise; 2) they lack knowledge of the system; 3) they do what they want in the organisation. The CEOs seldom reported that general management strategies were used to manage physicians. Instead, they described four types of physician-specific management strategies that were used in their organisations: organisational separation of physicians; "nagging and arguing"; compensations; relying on the physician role. These strategies seemed to reflect pragmatic behaviour on behalf of the managers that helped them to maintain control over physicians in daily work. However, in a longer perspective, they seemed to decrease the legitimacy of the manager role and also contribute to weakening of that role in the organisation.
CONCLUSIONS
Many CEOs seemed to regard the manager role in their organisations as weak and described difficulties in both taking and defining that role (for themselves or others) in relation to the physician role. Further research is needed to elucidate how managers in healthcare organisations assume the manager role in relation to the medical profession. Studies indicate that lack of clarity concerning manager role authority and responsibility may have negative consequences not only for the working conditions of managers, physicians, and other healthcare professionals, but also for the quality of care.
Publication
Journal: American Journal of Pharmaceutical Education
June/6/2011
Abstract
OBJECTIVE
To provide a longitudinal description of the variety of career paths and preparation strategies of pharmacy deans.
METHODS
A descriptive cross-sectional study design using survey research methodology was used. Chief executive officer (CEO) deans at every full and associate member institution of the American Association of Colleges of Pharmacy (AACP) in the United States as of May 1, 2009, were potential subjects.
RESULTS
The database housed 90.3% (N = 93) of all current (excluding interim/acting) CEO deans. Of the 4 cohorts across time (1991, 1996, 2002, and 2009 snapshots), the 2009 cohort had the highest percentage of deans following either the hierarchical or nontraditional career paths.
CONCLUSIONS
Deans named since 2002 have spent less time collectively in the professoriate than cohorts before them. One reason for this is the increase in the number of deans that followed nontraditional career paths and who spent little or no time in the professoriate prior to their first deanship. This also could be due to the increased demand for individuals to serve as dean due to retirements and the creation of new institutions.
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