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Publication
Journal: Science
July/25/2011
Publication
Journal: Angewandte Chemie - International Edition
May/20/2015
Abstract
The determination of structure-performance relationships of ceria in heterogeneous reactions is enabled by the control of the crystal shape and morphology. Whereas the (100) surface, predominantly exposed in nanocubes, is optimal for CO oxidation, the (111) surface, prevalent in conventional polyhedral CeO2 particles, dominates in C2H2 hydrogenation. This result is attributed to the different oxygen vacancy chemistry on these facets. In contrast to oxidations, hydrogenations on CeO2 are favored over low-vacancy surfaces owing to the key role of oxygen on the stabilization of reactive intermediates. The catalytic behavior after ageing at high temperature confirms the inverse face sensitivity of the two reaction families.
Publication
Journal: Healthcare quarterly (Toronto, Ont.)
August/18/2005
Abstract
To explore the current and pending strategic agenda of Ontario hospitals (the largest consumers of the provincial healthcare budget), a survey of Ontario acute care hospital CEOs was conducted in January 2004. The survey, with an 82% response rate, identifies 29 strategic priorities under seven key strategic themes consistent across different hospital types. These themes include (1) human resources cultivation, (2) service integration and partnerships, (3) consumer engagement, (4) corporate governance and management, (5) organizational efficiency and redesign, (6) improved information use for decision-making, (7) patient care management. The extent to which an individual hospital's control over strategic resolutions is perceived may affect multilevel strategic priority-setting and action-planning. In addition to supporting ongoing development of meaningful performance measures and information critical to strategic decision-making, this study's findings may facilitate a better understanding of hospitals' key resource commitments, the extent of competition and collaboration for key resources, the perceived degree of individual control over strategic issue resolution and where systemic resolutions may be required.
Publication
Journal: Issue brief (Commonwealth Fund)
August/26/2010
Abstract
Questions have been raised about whether and how health care quality improvement (QI) initiatives ought to be reviewed to address possible ethical issues associated with them. These questions have focused primarily on whether some QI initiatives meet the regulatory criteria for human subject research and should therefore be regulated and reviewed as such. Based on surveys of health care system professionals conducting QI initiatives and hospital CEOs, this issue brief finds that QI initiatives are routinely reviewed by a variety of internal mechanisms prior to implementation, although rarely through an institutional review board or another independent body charged specifically with ethical oversight of QI initiatives. Further research, the authors say, is needed to achieve a better understanding of how review mechanisms for QI initiatives are structured, including information on who reviews these activities, how they are reviewed, and whether such processes include an ethical assessment of the proposed QI initiative.
Publication
Journal: Environmental Pollution
January/18/2016
Abstract
Wastewater Treatment Plants (WWTPs) are a key pathway by which nanoparticles (NPs) enter the environment following release from NP-enabled products. This work considers the fate and exposure of CeO2 NPs in WWTPs in a two-step process of heteroaggregation with bacteria followed by the subsequent reduction of Ce(IV) to Ce(III). Measurements of NP association with solids in sludge were combined with experimental estimates of reduction rate constants for CeO2 NPs in Monte Carlo simulations to predict the concentrations and speciation of Ce in WWTP effluents and biosolids. Experiments indicated preferential accumulation of CeO2 NPs in biosolids where reductive transformation would occur. Surface functionalization was observed to impact both the distribution coefficient and the rates of transformation. The relative affinity of CeO2 NPs for bacterial suspensions in sludge appears to explain differences in the observed rates of Ce reduction for the two types of CeO2 NPs studied.
Publication
Journal: Health Policy
October/12/2009
Abstract
OBJECTIVE
The success of a Dutch program to disseminate quality improvement projects depends on the participation of physicians working in program hospitals. The leadership of hospital executives (CEOs) is considered an important explanation. This study aims to determine whether the relation, between the extent to which physicians notice their CEOs stimulate improvement initiatives and the number of projects joined by physicians, is moderated by the consensus among physicians working in the same hospital.
METHODS
Multilevel analyses are applied on data of 286 physicians from eight hospitals to: (1) estimate whether participation depends on noticing if CEOs stimulate improvement, (2) test if an individual's participation differs when more colleagues have the same opinion (effect modification).
RESULTS
Significant moderator effects are found. The participation of physicians, noticing that CEOs stimulate improvement is higher when more colleagues share this opinion. For physicians not knowing whether improvement is encouraged, higher consensus coincides with lower participation.
CONCLUSIONS
Project involvement of physicians depends on their consensus about encouragement by CEOs. This confirms the importance of strategic leaders in dissemination programs. Further research is recommended into causes of CEO leadership visibility and methods to strengthen leadership climate.
Publication
Journal: BMJ Open
January/7/2013
Abstract
OBJECTIVE
To identify the critical dimensions of hospital Chief Executive Officers' (CEOs) involvement in a quality and safety and to offer practical guidance to assist CEOs to fulfil their leadership role in quality improvement (QI).
METHODS
Qualitative interview study.
METHODS
20 organisations participating in the main phase of the Safer Patients Initiative (SPI) programme across the UK.
METHODS
17 CEOs overseeing 19 organisations participating in the main phase of the SPI programme and 36 staff (20 workstream leads, 10 coordinators and 6 managers) involved in SPI across all 20 participating organisations.
METHODS
Self-reported perceptions of CEOs on their contribution and involvement within the SPI programme, supplemented by staff peer-reports.
RESULTS
The CEOs recognised the importance of their part in the SPI programme and gave detailed accounts of the perceived value that their involvement had brought at all stages of the process. In exploring the parts played by the CEOs, five dimensions were identified: (1) resource provision; (2) staff motivation and engagement; (3) commitment and support; (4) monitoring progress and (5) embedding programme elements. Staff reports confirmed these dimensions; however, the weighting of the dimensions differed. The findings stress the importance of particular actions of support and monitoring such as constant communication through leadership walk rounds and reviewing programme progress and its related clinical outcomes at Board meetings.
CONCLUSIONS
This study addressed the call for more research-informed practical guidance on the role of senior management in QI s. The findings show that the CEOs provided key participation considered to significantly contribute towards the SPI programme. CEOs and staff identified a number of clear and consistent themes essential to organisation safety improvement. Queries raised include the tangible benefits of executive involvement in changing structures and embedding for sustainability and the practical steps to creating the 'right' environment for QI.
Publication
(16626440; CEO; 10.1111/j.1442-9071.2006.01180.x)
Journal: Clinical and Experimental Ophthalmology
June/11/2006
Abstract
Decompression retinopathy has been reported as a rare occurrence, subsequent to Nd:YAG laser peripheral iridotomy for the treatment of acute angle closure. Herein a case of a 67-year-old woman is described who developed decompression retinopathy in conjunction with unexpectedly severe corneal stromal oedema following Nd:YAG laser peripheral iridotomy for acute angle closure. The literature regarding these phenomena is reviewed.
Publication
Journal: Journal of Hazardous Materials
May/30/2012
Abstract
To characterize the environmental transport and quantify the risk of nanoparticles (NPs), it is important to fundamentally understand the aggregation of NPs and to describe this process quantitatively. This study investigates the aggregation kinetics of CeO(2) NPs in the presence of KCl, CaCl(2) and humic acid (HA) using time-resolved dynamic light scattering. In KCl solutions, regardless of their concentration, HA drastically reduces the aggregation kinetics of CeO(2) NPs. However, the effect of HA was more complicated in CaCl(2) solutions. At low CaCl(2) concentrations, HA inhibited NP aggregation, whereas at high CaCl(2) concentrations, HA promoted aggregation. The critical coagulation concentration (CCC) in KCl in the absence of HA is approximately 36.5mM. In presence of both 1 ppm and 10 ppm HA in KCl solutions, extremely low aggregation kinetics were observed even at very high KCl concentrations (500 mM), implying KCl-CCCs in presence of HA were larger than 500 mM. The CCCs under conditions of no HA, 1 ppm HA and 10 ppm HA in CaCl(2) solutions are approximately 9.5, 8.0 and 12.0mM, respectively. These observations were analyzed in the framework of extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory. Moreover, a kinetic model was used to predict the aggregation kinetics of CeO(2) NPs. The model predictions are in close agreement with experimental observations. To the best of our knowledge, this work is the first to model quantitatively the aggregation of NPs in the presence of natural organic matter.
Publication
Journal: PLoS ONE
June/27/2016
Abstract
During mammalian oocyte growth, genomic DNA may accumulate DNA double-strand breaks (DSBs) induced by factors such as reactive oxygen species. Recent evidence demonstrated that slight DSBs do not activate DNA damage checkpoint proteins in denuded oocytes. These oocytes, even with DNA DSBs, can resume meiosis and progress to metaphase of meiosis II. Meiotic resumption in oocytes is also controlled by the surrounding cumulus cells; accordingly, we analyzed whether cumulus-cell enclosed oocytes (CEOs) with DNA damage are able to resume meiosis. Compared with DNA-damaged denuded oocytes, we found that meiotic resumption rates of CEOs significantly decreased. To assess the mechanism by which cumulus cells block meiotic resumption in CEOs with DNA DSBs, we treated the cumulus oocyte complex with the gap junction inhibitor carbenoxolone and found that carbenoxolone can rescue the block in CEO meiosis induced by DNA DSBs. Since cumulus cell-synthesized cAMPs can pass through the gap junctions between oocyte and cumulus cell to block oocyte meiosis, we measured the expression levels of adenylate cyclase 1 (Adcy1) in cumulus cells, and G-protein coupled receptor 3 (Gpr3) and phosphodiesterase 3A (Pde3a) in oocytes, and found that the mRNA expression level of Adcy1 increased significantly in DNA-damaged cumulus cells. In conclusion, our results indicate that DNA DSBs promote cAMP synthesis in cumulus cells, and cumulus cAMPs can inhibit meiotic resumption of CEOs through gap junctions.
Publication
Journal: Journal of Physical Chemistry B
June/26/2007
Abstract
The thermal decomposition of hydrogen peroxide, H(2)O(2), was determined in aqueous suspensions of SiO(2), Al(2)O(3), TiO(2), CeO(2), and ZrO(2) nanometer-sized particles. First-order kinetics were observed for the decomposition in all cases. Temperature dependence studies found that the activation energy was 42 +/- 5 kJ/mol for the overall decomposition of H(2)O(2) independent of the type of oxide. Oxide type had a strong effect on the pre-exponential rate term with increasing rate in the order of SiO(2) < Al(2)O(3) < TiO(2) < CeO(2) < ZrO(2). The rate coefficient for H(2)O(2) decomposition increases with increasing surface area of the oxide, but the number or efficiency of reactive sites rather than the total surface area may have the dominant role. Very efficient scavengers for OH radicals in the bulk liquid are not able to prevent formation of molecular oxygen, the main H(2)O(2) gaseous decay product, suggesting that decomposition occurs on the oxide surfaces. The decomposition of H(2)O(2) in the gamma-radiolysis of water is enhanced by the addition of ceramic oxides, possibly due to excess formation of hydrated electrons from energy deposited in the solid.
Publication
Journal: Occupational Medicine
October/15/2003
Abstract
OBJECTIVE
To identify the salient magnetic resonance imaging (MRI) features of tennis elbow. An objective diagnosis is important when managing work-related incapacity due to ill-defined lateral arm pain.
METHODS
Twenty-three symptomatic and 17 asymptomatic elbows in 20 patients with tennis elbow, no evidence of other pathology and no previous treatment were imaged using established MRI sequences.
RESULTS
In the symptomatic elbows, the common extensor origin (CEO) showed signs of oedema in 23, thickening in 19, peri-tendon oedema in 3 and tears in 13 cases. More extensive abnormalities were demonstrated in only two elbows. Six out of 17 asymptomatic elbows also showed oedema in the CEO.
CONCLUSIONS
The CEO is confirmed as the primary site of MRI changes in tennis elbow. Oedema was commonly found in asymptomatic elbows, necessitating the presence of thickening or tears in the CEO tendon to objectively diagnose tennis elbow on MRI.
Publication
Journal: BMC Health Services Research
August/4/2009
Abstract
BACKGROUND
The aim of this study was to assess the outsourcing situation in Taiwanese hospitals and compares the differences in hospital ownership and in accreditation levels.
METHODS
This research combined two kinds of methods: a questionnaire survey and the in-depth interview to two CEOs of the sample hospitals. One hospital is not-for-profit, while the other is a public hospital and the research samples are from the hospital data from Taiwan's 2005 to 2007 Department of Health qualifying lists of hospital accreditation. The returned questionnaires were analyzed with STATISTICA 7.1 version software.
RESULTS
The results for non-medical items showed medical waste and common trash both have the highest rate (94.6 percent) of being outsourced. The gift store (75 percent) and linen (73 percent) follow close behind, while the lowest rate of outsourcing is in utility maintenance (13.5 percent). For medical items, the highest rate of outsourcing is in the ambulance units (51.4 percent), while the hemodialysis center follows close behind with a rate of 50 percent. For departments of nutrition, pharmacy, and nursing however, the outsourcing rate is lower than 3 percent. This shows that Taiwan's hospitals are still conservative in their willingness to outsource for medical items. The results of the satisfaction paired t-test show that the non-medical items have a higher score than the medical items. The factor analysis showed the three significant factors in of non medical items' outsourcing are "performance", "finance", and "human resource". For medical items, the two factors are "operation" and satisfaction". To further exam the factor validity and reliability of the satisfaction model, a confirmative factor analysis (CFA) was conducted using structure equation modeling (SEM) method and found the model fitting well.
CONCLUSIONS
Hospitals, especially for public hospitals, can get benefits from outsourcing to revive the full-time-equivalent and human resource limitation.
Publication
Journal: Biosensors and Bioelectronics
May/25/2009
Abstract
A novel nanocomposite membrane, comprising of nanosized shuttle-shaped cerium oxide (CeO(2)), single-walled carbon nanotubes (SWNTs) and hydrophobic room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF(6)), was developed on the glassy carbon electrode (GCE) for electrochemical sensing of the immobilization and hybridization of DNA. The properties of the CeO(2)-SWNTs-BMIMPF(6)/GCE, the characteristics of the immobilization and hybridization of DNA were studied by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) using [Fe(CN)(6)](3-/4-) as the redox indicator. The synergistic effect of nano-CeO(2), SWNTs and RTIL could dramatically enhance the sensitivity of DNA hybridization recognition. The electron transfer resistance (R(et)) of the electrode surface increased after the immobilization of probe ssDNA on the CeO(2)-SWNTs-BMIMPF(6) membrane and rose further after the hybridization of the probe ssDNA with its complementary sequence. The remarkable difference between the R(et) value at the probe DNA-immobilized electrode and that at the hybridized electrode could be used for label-free EIS detection of the target DNA. The sequence-specific DNA of phosphoenolpyruvate carboxylase (PEPCase) gene from transgenically modified rape was detected by this DNA electrochemical biosensor. Under optimal conditions, the dynamic range for detecting the sequence-specific DNA of the PEPCase gene was from 1.0x10(-12) mol/L to 1.0x10(-7) mol/L, and the detection limit was 2.3x10(-13) mol/L, suggesting that the CeO(2)-SWNTs-BMIMPF(6) nanocomposite hold great promises for the applications in sensitive electrochemical biosensor.
Publication
Journal: Endocrinology
September/25/2007
Abstract
Steroids mediate the gonadotropic stimulus of oocyte maturation in fish and amphibians. Such a role of steroids in mammals has not been confirmed until recently. A series of studies presented data suggesting that steroids might be involved in meiosis of mouse oocytes. Here we examined this suggestion using in vitro cultures of rat and mouse follicle-enclosed oocytes (FEOs) and cumulus-enclosed oocytes (CEOs). In FEOs that mature only in response to gonadotropins or other stimuli, we tested the ability of steroids to trigger meiosis and whether addition of steroid receptor antagonists blocks LH/human chorionic gonadotropin stimulation of meiosis. In CEOs that mature spontaneously, we tested whether steroid antagonists block maturation and whether steroids overcome the inhibition of maturation by hypoxanthine (Hx), a mild inhibitor of meiotic resumption. The progesterone antagonists mifepristone (RU 486) and Organon 31710 as well as the estrogen antagonist faslodex did not prevent LH-triggered maturation of rat or mouse FEOs or the spontaneous maturation of CEOs. In accordance, the progesterone agonist promegestone (R5020) and estradiol did not stimulate the resumption of meiosis in rat and mouse FEOs, and both did not overcome the Hx inhibition of meiosis in rat and mouse CEOs. Flutamide, an androgen antagonist, did block meiosis in rat FEOs, but this action could not be affected by adding dihydrotestosterone, suggesting that it was not androgen receptor mediated. Flutamide did not affect spontaneous maturation of rat CEOs, and dihydrotestosterone could not stimulate meiosis inhibited by Hx. Thus, in contrast to lower vertebrates, in mammals, steroids do not seem to serve as an obligatory signal by which the somatic cells of the follicle transfer the gonadotropic stimulation of meiosis to the oocyte.
Publication
Journal: Journal of Physical Chemistry B
August/24/2011
Abstract
Nonadiabatic dynamics generally defines the entire evolution of electronic excitations in optically active molecular materials. It is commonly associated with a number of fundamental and complex processes such as intraband relaxation, energy transfer, and light harvesting influenced by the spatial evolution of excitations and transformation of photoexcitation energy into electrical energy via charge separation (e.g., charge injection at interfaces). To treat ultrafast excited-state dynamics and exciton/charge transport we have developed a nonadiabatic excited-state molecular dynamics (NA-ESMD) framework incorporating quantum transitions. Our calculations rely on the use of the Collective Electronic Oscillator (CEO) package accounting for many-body effects and actual potential energy surfaces of the excited states combined with Tully's fewest switches algorithm for surface hopping for probing nonadiabatic processes. This method is applied to model the photoinduced dynamics of distyrylbenzene (a small oligomer of polyphenylene vinylene, PPV). Our analysis shows intricate details of photoinduced vibronic relaxation and identifies specific slow and fast nuclear motions that are strongly coupled to the electronic degrees of freedom, namely, torsion and bond length alternation, respectively. Nonadiabatic relaxation of the highly excited mA(g) state is predicted to occur on a femtosecond time scale at room temperature and on a picosecond time scale at low temperature.
Publication
Journal: Journal of Medical Genetics
July/19/1995
Abstract
In a fragile X family referred for prenatal diagnosis, the female fetus did not inherit the full fragile X mutation from her mother, but an unexpected expansion within the normal range of CGG repeats from 29 to 39 was observed in the paternal X chromosome. Also, a rare recombination between DXS548 and FRAXAC1 was recorded in the maternal meiosis. Follow up of the neonate confirmed the same DNA genotype as in the CVS, but the child died of DiGeorge syndrome after four days and was subsequently found to carry a microdeletion of chromosome 22 using probe cEO. It is suggested that in this family the deletion of chromosome 22 is likely to be a chance event but the rare recombinant and the fragile X mutation might be causally related.
Publication
Journal: Health Services Research
September/8/1993
Abstract
OBJECTIVE
Two theories--agency and managerialism--are compared with respect to their usefulness in explaining the role of insiders on the hospital board: whether their participation enhances or impairs board financial decision making.
METHODS
The study used 1985 hospital financial and governing board data for a representative sample of acute care California hospitals.
METHODS
Relationships were examined cross-sectionally between the presence or absence of insiders on the board and measures of hospital financial viability while controlling for the organizational factors of system affiliation, ownership, size, region, and corporate restructuring.
RESULTS
Multiple regression analysis found significant relationships between insider (CEO, medical staff) participation and hospital viability.
CONCLUSIONS
These results support the managerial theory of governance by suggesting that the CEO and medical staff provide informational advantages to the hospital governing board. However, the cross-sectional design points to the need for future longitudinal studies in order to sequence these relationships between insider participation and improved hospital viability.
Publication
Journal: Inorganic Chemistry
February/28/2012
Abstract
Thin films of ceria (CeO(2)) have many applications, and their synthesis by liquid-injection MOCVD (metal-organic chemical vapor deposition) or ALD (atomic layer deposition) requires volatile precursor compounds. Here we report the synthesis of a series of homoleptic and heteroleptic Ce(IV) complexes with donor-functionalized alkoxide ligands mmp (1-methoxy-2-methylpropan-2-olate), dmap (1-(dimethylamino)propan-2-olate), and dmop (2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)propan-2-olate) and their potential as precursors for MOCVD and ALD of CeO(2). New complexes were synthesized by alcohol exchange reactions with [Ce(OBu(t))(4)]. [Ce(mmp)(4)] and [Ce(dmap)(4)] were both found to be excellent precursors for liquid-injection MOCVD of CeO(2), depositing high purity thin films with very low carbon contamination, and both have a large temperature window for diffusion controlled growth (350-600 °C for [Ce(mmp)(4)]; 300-600 °C for [Ce(dmap)(4)]). [Ce(mmp)(4)] is also an excellent precursor for liquid-injection ALD of CeO(2) using H(2)O as oxygen source and demonstrates self-limiting growth from 150 to 350 °C. [Ce(dmap)(4)] has lower thermal stability than [Ce(mmp)(4)] and does not show self-limiting growth in ALD. Heteroleptic complexes show a tendency to undergo ligand redistribution reactions to form mixtures in solution and are unsuitable as precursors for liquid-injection CVD.
Publication
Journal: Chemical Research in Toxicology
April/3/1994
Abstract
The cytochromes P450 (P450) involved in the epoxidation of the rat carcinogen acrylonitrile (ACN) to the mutagen 2-cyanoethylene oxide (CEO) have been investigated in hepatic microsomes from F-344 rats and humans. Induction of P450 2E1 by acetone treatment increased the Vmax for rat microsomal CEO formation 5-fold, while ACN treatment had little effect. Treatment with beta-naphthoflavone, dexamethasone, and phenobarbital had little effect upon Vmax but increased the KM 3- to 5-fold. The P450 ligand 1-phenylimidazole and substrate ethanol were potent inhibitors of ACN epoxidation after all treatments. 2-(Diethylamino)ethyl 2,2-diphenylvalerate (SKF 525A; 0.1 mM) was not an effective inhibitor with microsomes from untreated or acetone-treated rats, but inhibited approximately 50% following dexamethasone or phenobarbital treatment. Antibodies to P450 2E1 inhibited>> 85% of the ACN epoxidation activity in microsomes from untreated or beta-naphthoflavone- or acetone-treated rats, but only produced 40% and 60% inhibition following dexamethasone or phenobarbital treatments, respectively. These results indicate that P450 2E1 is the major catalyst of ACN epoxidation in untreated rats and that other forms of P450 can also epoxidize ACN. Diethyldithiocarbamate (0.1 mM) was a potent irreversible inhibitor of ACN epoxidation after all of the induction treatments, indicating that it is not specific for P450 2E1. Chlorzoxazone (2 mM) produced 75-90% inhibition after all of the induction treatments, indicating that it interacts with several rodent P450 isoforms in addition to 2E1. Human hepatic microsomes (n = 6) epoxidized ACN with Vmax'S ranging from 129 to 315 pmol of CEO formed/(min.mg of protein) and KM's from 12 to 18 microM.(ABSTRACT TRUNCATED AT 250 WORDS)
Publication
Journal: Avian Pathology
October/26/2008
Abstract
In a recent study (Oldoni & García, 2007), some field strains of infectious laryngotracheitis viruses (ILTV) were characterized as genotypically different (group VI) from ILT vaccine strains. The objective of this study was to evaluate the protection elicited by one chicken embryo origin (CEO) and one tissue culture origin (TCO) vaccine against a field isolate from group VI after direct and indirect exposure to ILTV live attenuated vaccines. In phase 1 of the experiment, non-vaccinated chickens were placed into contact with the eye drop vaccinates for a period of four weeks after vaccination. Transmission of the vaccine virus to these in-contact birds was demonstrated by real time PCR and antibody production, although the in-contact birds did not become protected against disease when subsequently challenged in phase 2 of the experiment. This emphasized the importance of uniform vaccination to obtain adequate protection, both to avoid the occurrence of susceptible chickens, and to minimize the potential for reversion to virulence of live-attenuated vaccines. In phase 2, protection against challenge with a group VI field virus was assessed four weeks after vaccination by scoring clinical signs and mortality, and quantifying weight gain. Sentinel birds were added to the groups one day after challenge to assess shedding of challenge virus, using real time PCR and virus isolation, during the period 2 to 12 days post challenge. The results showed that the CEO and TCO eye drop-vaccinated chickens were protected against challenge with the group VI virus, even though it was genetically different from the vaccine strains, and that challenge virus was not transmitted from these protected birds to the sentinels.
Publication
Journal: Drug Metabolism and Disposition
January/26/2003
Abstract
Acrylonitrile (AN) is a rodent carcinogen and suspected human carcinogen. Metabolism of AN proceeds via conjugation with glutathione or epoxidation via cytochrome P4502E1 (CYP2E1) to cyanoethylene oxide (CEO). It was hypothesized that CEO metabolism via epoxide hydrolase (EH) is the primary pathway for cyanide formation. The objective of this work is to assess the enzymatic basis of metabolism to cyanide. Male wild-type and CYP2E1-null mice received 0, 2.5, 10, 20, or 40 mg of AN/kg by gavage, and cyanide was measured in blood and tissues. CYP2E1 and EH expression were assessed using Western blot analyses. Present results demonstrated that cyanide concentrations in blood and tissues of AN-treated wild-type mice were higher at 1 versus 3 h, increased in a dose-dependent manner, and were significantly higher in AN-treated versus vehicle-treated mice. In contrast, cyanide concentrations in the blood and tissues of AN-treated CYP2E1-null mice were not statistically different from those of vehicle-treated mice. Furthermore, this work showed that EH is expressed in CYP2E1-null and wild-type mice. In conclusion, under the current experimental conditions using CYP2E1-null mice, current work demonstrated for the first time that CYP2E1-mediated oxidation is a prerequisite for AN metabolism to cyanide. Since earlier studies showed that CYP2E1 is the only enzyme responsible for AN epoxidation, it is concluded that AN metabolism to CEO is a prerequisite for cyanide formation, and this pathway is exclusively catalyzed by CYP2E1. Finally, this work confirmed that cyanide plays an essential role in the causation of the acute toxicity/mortality of AN.
Publication
Journal: International Journal of Biological Macromolecules
July/14/2017
Abstract
In this study cinnamon essential oil-incorporated chitosan nanoparticles (CEO-CSNPs) were produced by an emulsion-gelation method. Size, zeta potential and polydispersity index of the formed nanoparticles were 235.6nm, 25.1mV and 0.33, respectively. In vitro release evaluation showed an initial burst effect, followed by a slow CEO release during 104h (at pH∼5). Different formulations of patties including control, samples containing free and encapsulated CEO and ascorbic acid were analyzed for physicochemical characteristics, microbial growth and sensorial attributes during 8days of storage at 4°C. Both free and encapsulated CEO decreased the microbial population of patties compared to the control (p<0.05) throughout the experiment. On the 8th day, the best formulations in TBARS test were AA-0.05 (0.05% of ascorbic acid) and 0.1-EN-CEO (0.1% of encapsulated CEO). During storage, the color parameters of the patties containing encapsulated CEO changed slightly whereas color and metmyoglobin content significantly decreased in samples containing free CEO and control. Free CEO had an unfavorable impact on color and odor but the incorporation of encapsulated CEO improved the consumer acceptability. The principle component analysis clearly distinguished 6 formulation groups based on physicochemical characteristics.
Publication
Journal: Physical Chemistry Chemical Physics
June/18/2009
Abstract
Oxygen transport in rare-earth oxide (RE(2)O(3)) doped CeO(2) with fluorite structure has attracted considerable attention owing to both the range of practical usage (e.g., fuel cells, sensors, etc.) and the fundamental fascination of fast oxide ion transport in crystalline solids. Using density-functional theory, we have calculated the formation energies of point defects and their migration properties in RE(2)O(3) doped CeO(2)(RE = Sc, Y, La, Nd, Sm, Gd, Dy, and Lu). The calculated results show that oxygen vacancies are the dominant defect species obtained by RE(3+) doping. They form associates with the RE(3+) ions, and the corresponding defect association energy is a strong function of the ionic radii of the RE(3+) dopants. The migration of an oxygen vacancy was investigated using the nudged elastic band method. The lowest activation energy for oxygen vacancy hopping is obtained for a straightforward migration path between two adjacent oxygen sites. The migration energy of an oxygen vacancy also strongly depends on the ionic radii of the neighbouring dopant cations. Accordingly, we have identified two factors that affect the oxygen vacancy migration; (1) trapping (or repelling) of an oxygen vacancy at the NN site of the RE(3+) dopant, and (2) reduction (or enlargement) of the migration barrier by RE(3+) doping. These findings provide insight for atomistic level understanding of ionic conductivity in doped ceria and would be beneficial for optimizing ionic conductivity.
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