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Publication
Journal: Molecular Reproduction and Development
April/28/1991
Abstract
The present study was carried out to examine the role of protein synthesis in mouse oocyte maturation in vitro. In the first part of this study, the effects of cycloheximide (CX) were tested on spontaneous meiotic maturation when oocytes were cultured in inhibitor-free medium. CX reversibly suppressed maturation of oocytes as long as maturation was either initially prevented by the phosphodiesterase inhibitor, 3-isobutyl-1-methyl-xanthine (IBMX), or delayed by follicle-stimulating hormone (FSH). In the second part of this study, the actions of protein synthesis inhibitors were tested on hormone-induced maturation. CEO were maintained in meiotic arrest for 21-22 h with hypoxanthine, and germinal vesicle breakdown (GVB) was induced with follicle-stimulating hormone (FSH). Three different protein synthesis inhibitors [CX, emetine (EM), and puromycin (PUR)] each prevented the stimulatory action of FSH on GVB in a dose-dependent fashion. This was accompanied by a dose-dependent suppression of 3H-leucine incorporation by oocyte-cumulus cell complexes. The action of these inhibitors on FSH- and epidermal growth factor (EGF)-induced GVB was next compared. All three drugs lowered the frequency of GVB in the FSH-treated groups, below even that of the controls (drug + hypoxanthine); the drugs maintained meiotic arrest at the control frequencies in the EGF-treated groups. Puromycin aminonucleoside, an analog of PUR with no inhibitory action on protein synthesis, had no effect. The three inhibitors also suppressed the stimulatory action of FSH on oocyte maturation when meiotic arrest was maintained with the cAMP analog, dbcAMP.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors
Publication
Journal: Theriogenology
October/12/2000
Abstract
This study evaluated the effect of forskolin and FSH on pig oocyte maturation when cultured in a maturation inhibiting system. Ovaries from prepubertal gilts were collected at a local slaughterhouse. Oocytes were cultured in a hypoxanthine (HX 4 mM) containing M 199 for 24 or 40 h with or without forskolin and FSH treatment. After the culture, we examined germinal vesicle breakdown (GVBD) and polar body (PB) formation. Two experiments were designed. (1) Cumulus enclosed oocytes (CEO) were cultured for 24 or 40 h with or without different doses of forskolin and FSH. (2) CEO were primed by forskolin and FSH for different times and then transferred into an HX-medium for a further culture. The total culture period was 24 h. The results revealed that 4 mM HX markedly prevented pig CEO from undergoing GVBD. After 24 and 40 h culture, FSH (50-200 U/L) stimulated oocytes to resume meiosis by overcoming the inhibition of HX. Both GVBD and PB formation were increased (P < 0.002 and 0.01 respectively) after 40 h exposed to FSH. Forskolin showed a biphasic effect on CEO maturation. Within 24 h forskolin, in combination with HX, inhibited oocytes maturation. The GVBD percentage was significantly decreased compared to HX alone group (2% to 20%, P < 0.01), whereas no inhibition was observed after 40 h of culture. The second experiment showed that forskolin (3 microM) and FSH (100 U/L) priming CEO could time-dependently induce oocyte maturation by overriding the inhibition of HX. After 30 and 60 min priming by FSH or forskolin, the GVBD and PB percentage was significantly increased (P < 0.002 and 0.01 respectively). No difference of GVBD percentage was observed between FSH short time priming group and FSH long time presentation group. In conclusion, we found that forskolin and FSH in vitro can stimulate pig cumulus cells to secrete a meiosis-activating substance which induces the oocyte to overcome the inhibition of hypoxanthine and undergo GVBD.
Publication
Journal: Journal of Neurosurgical Anesthesiology
April/4/2012
Abstract
BACKGROUND
Acute normovolemic hemodilution (ANH) is used in major surgery expected to be accompanied by excessive blood loss. Reducing the hemoglobin content may disturb cerebral oxygen balance. The aim of this study was to assess the effect of ANH on cerebral oxygen balance in patients subjected to brain tumor resection.
METHODS
Forty patients were randomly allocated into 2 groups (hemodilution and control). In the hemodilution group (HG), 1000 mL of blood was drawn and replaced with the same volume of HES 130/0.4 (6%, Voluven) colloid. In the control group (CG), no blood was drawn, and hemodynamics were stabilized using normal saline until allogenic blood was needed. Arterial and jugular bulb blood samples obtained after induction (basal, sample 1), 40 minutes after induction (or on completion of hemodilution, sample 2), after surgical hemostasis (sample 3), and just before extubation (sample 4) were used for the calculation of arterial-jugular oxygen content difference "Ca-jO(2)," cerebral oxygen extraction "CEO(2)," estimated cerebral metabolic rate for oxygen "eCMRO(2)," cerebral blood flow equivalent "CBFe," and jugular-arterial lactate difference "J-ALD" in both groups.
RESULTS
Jugular oxygen saturation "SjvO(2)", CEO(2), and J-ALD showed no significant difference when the 2 groups were compared at the corresponding time points and when the values obtained at different time points were compared with the basal value in the same group. In CG, "Ca-jO(2)" significantly decreased at the end of surgery and before tracheal extubation (P<0.003 and 0.002, respectively). In HG, it decreased after hemodilution, with P value of less than 0.032. eCMRO(2) was significantly reduced in CG 40 minutes after induction of anesthesia, at the end of surgery, and before tracheal extubation (P<0.021, 0.001, and 0.001, respectively). In HG, eCMRO(2) was significantly reduced at the end of hemodilution and at the end of surgery with P value of less than 0.005 and 0.034, respectively. CBFe was significantly increased in CG at the end of surgery and before tracheal extubation (P<0.005 and 0.022, respectively). It was also increased after hemodilution in HG (P<0.042). There were no significant differences in Ca-jvO(2), eCMRO(2), and CBFe between the 2 groups.
CONCLUSIONS
ANH and allogenic blood transfusion used in this study design were accompanied by comparable cerebral oxygenation parameters in patients subjected to brain tumor resection.
Publication
Journal: Inorganic Chemistry Communication
February/19/2017
Abstract
In this paper we report the enzymatic properties of Ti-doped CeO(2) nanoparticles. The superoxide dismutase activity of Ti-doped nanoparticles is reduced in comparison to undoped nanoceria. In contrast, the oxidase activity of these nanoparticles was unchanged. The change in enzymatic activity was accompanied by a dramatic change in shape to a spherical nanostructure. In addition to reporting a new type of enzymatically-active nanoparticle, Ti-doped cerium oxide nanoparticles are well suited for biological applications.
Publication
Journal: Environmental Science & Technology
May/28/2012
Abstract
The alkali metal-induced deactivation of a novel CeO(2)-WO(3) (CeW) catalyst used for selective catalytic reduction (SCR) was investigated. The CeW catalyst could resist greater amounts of alkali metals than V(2)O(5)-WO(3)/TiO(2). At the same molar concentration, the K-poisoned catalyst exhibited a greater loss in activity compared with the Na-poisoned catalyst below 200 °C. A combination of experimental and theoretical methods, including NH(3)-TPD, DRIFTS, H(2)-TPR, and density functional theory (DFT) calculations, were used to elucidate the mechanism of the alkali metal deactivation of the CeW catalyst in SCR reaction. Experiments results indicated that decreases in the reduction activity and the quantity of Brønsted acid sites rather than the acid strength were responsible for the catalyst deactivation. The DFT calculations revealed that Na and K could easily adsorb on the CeW (110) surface and that the surface oxygen could migrate to cover the active tungsten, and then inhibit the SCR of NO(x) with ammonia. Hot water washing is a convenient and effective method to regenerate alkali metal-poisoned CeW catalysts, and the catalytic activity could be recovered 90% of the fresh catalyst.
Publication
(16764662; CEO; 10.1111/j.1442-9071.2006.01228.x)
Journal: Clinical and Experimental Ophthalmology
August/7/2006
Abstract
This report describes the features, treatment and outcome of globe perforation by a Taser dart electrode in a 21-year-old man. The Taser electrode caused mechanical iris, lens and retinal injury and consequent retinal detachment as result of proliferative vitreoretinopathy. The effect of electrical stimulation on ocular tissues is unknown. After the scleral and corneal wounds, traumatic cataract and retinal tear were repaired, the patient regained a visual acuity of 6/18. Nine months later a retinal detachment with proliferative vitreoretinopathy was discovered. The Taser may cause globe perforation and posterior segment injury. Understanding the barbed configuration of the dart electrode is important when extricating this device. Visual recovery is possible despite electric discharge of the Taser and suggests that the mechanism of ocular injury is largely mechanical.
Publication
Journal: International Journal of Health Planning and Management
August/8/2018
Abstract
Outsourcing is used as a strategy to improve efficiency, quality, and satisfaction of beneficiaries in hospitals. This study aimed to determine the reasons for outsourcing, outsourced services, achieved objectives, and outsourcing challenges. This qualitative study was conducted through 58 face-to-face semi-structured interviews with chief executive officers (CEOs), chief financial officers (CFOs), and contracting experts (CEs) in 42 public hospitals in Tehran, Iran. Purposive and snowball sampling techniques were used. Interviews were recorded digitally and transcribed verbatim. Data analysis was performed based on an inductive-deductive approach via MAXQDA-10. The Participants included 26 CEOs, 15 CFOs, and 17 CEs. The most important reasons for outsourcing were divided into four main categories including financial resources and funding, customers, management, and factors related to the hospitals. Accessing to up-to-date knowledge and technology, improving service quality and accountability, focusing on strategic points, reducing workload, and increasing patient satisfaction turned out to be the positive outcomes of outsourcing. Weakness in laws and regulations, monitoring and assessment of an outsourced unit, creating dependency and changing organizational culture, as well as human resource issues were introduced as the main pitfalls and challenges of outsourcing. Based on the results, it was suggested that the hospital managers must attempt to outsource services by realistic analysis of the organization's current status. They should specify the reasons and objectives of outsourcing and make decisions based on outsourcing potentials. By taking the current challenges of outsourcing in Iranian hospitals into account, the authorities can make the most efficient decisions with regard to outsourcing.
Publication
Journal: ACS Applied Materials & Interfaces
October/8/2014
Abstract
Preparation of bismuth vanadate and cerium dioxide (BiVO4/CeO2) nanocomposites as visible-light photocatalysts was successfully obtained by coupling a homogeneous precipitation method with hydrothermal techniques. The BiVO4/CeO2 nanocomposites with different mole ratios were synthesized and characterized by X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). Absorption range and band gap energy, which are responsible for the observed photocatalyst behavior, were investigated by UV-vis diffuse reflectance (UV-vis DR) spectroscopy. Photocatalytic activities of the prepared samples were examined by studying the degradation of model dyes Methylene Blue, Methyl Orange, and a mixture of Methylene Blue and Methyl Orange solutions under visible-light irradiation (>400 nm). Results clearly show that the BiVO4/CeO2 nanocomposite in a 0.6:0.4 mol ratio exhibited the highest photocatalytic activity in dye wastewater treatment.
Publication
Journal: International Journal of Molecular Sciences
November/17/2014
Abstract
The present work provides a comprehensive overview of the recent progress of research work toward developing new one dimensional (1-D) ceria (CeO(2)) nanomaterials. The review has been classified into three parts: the preparation procedures with identification of the existing different dimensional ceria nanomaterials, the formation mechanisms, and an analysis of their applications. From literature survey, it is inaugurated that the fundamental structures of the ceria nanomaterials constructively dominate their properties and applications. In addition, this work will also provide a perspective on the future technical trends for the development of different dimensional CeO(2) nanomaterials.
Publication
Journal: Chemical Communications
December/7/2011
Abstract
We present a simple method to gradually tune the size and to induce the shape change of CeO(2) nanoparticles via increasing the content of Yb(3+) doping.
Publication
Journal: Bioresource Technology
June/17/2012
Abstract
This study investigated the fate of nano-CeO(2) during municipal wastewater treatment using a laboratory-scale activated sludge (A/S) system fed with primarily-treated municipal wastewater and nano-CeO(2) (55.0 mg Ce/L). Nano-CeO(2) was highly removed during A/S treatment (96.6% total Ce). Extensive removal of CeO(2) <200 nm was also attained and the concentration escaping treatment was only 0.11 mg Ce/L. Elimination occurred mainly by aggregation and settling of CeO(2) particles, promoted by circumneutral pH values and by nanoparticle interactions with organic and/or inorganic wastewater constituents. Biosorption also contributed to CeO(2) removal as shown by sludge analysis and batch adsorption studies. Batch bioassays demonstrated that nano-CeO(2) only exerted inhibition of O(2) uptake by A/S at concentrations exceeding those in the bioreactor feed (50% inhibition at 950 mg CeO(2)/L). These findings indicate that A/S treatment is expected to provide extensive removal of nano-CeO(2) in municipal wastewaters.
Publication
Journal: Physical Chemistry Chemical Physics
February/2/2011
Abstract
Thin films of CeO(2) (both nominally pure and 10 mol% gadolinium-doped) grown via pulsed-laser deposition were studied. The electrical conductivity of the samples was measured as a function of thickness, temperature and oxygen partial pressure (pO(2)) using impedance spectroscopy. As expected, undoped CeO(2) exhibits electronic conductivity (with activation energy between 1.4 and 1.6 eV) whereas the highly doped samples are oxygen vacancy conductors (activation energy around 0.7 eV for epitaxial films). In order to investigate the influence of the nature of the substrate the thin films were grown on two different substrates, Al(2)O(3) (0001) and SiO(2) (0001), and compared. While the films grown on SiO(2) exhibit a microstructure characterized by columnar grains, the films grown on Al(2)O(3) are epitaxial. Notably, for films on both substrates the conductivity and activation energy vary with film thickness and exhibit remarkable differences when the films on different substrates are compared. In the case of the polycrystalline films (SiO(2) substrate), the space charge layer effects of the grain boundaries dominate over the substrate-film interface effect. In the case of the epitaxial films (Al(2)O(3) substrate), a small interface effect, probably due to a space charge layer or structural strain, is observed.
Publication
Journal: Langmuir
July/29/2013
Abstract
Supercritical fluids offer fast and facile routes toward well-crystallized tailor-made cerium oxide nanoparticles. However, the use of surfactants to control morphology and surface properties remains essential. Therefore, although water, near-critical (nc) or supercritical (sc), is a solvent of choice, the poor water solubility of some surfactants could require other solvent systems such as alcohols, which could themselves behave as surface modifiers. In here, the influence of seven different alcohols, MeOH, EtOH, PrOH, iPrOH, ButOH, PentOH, and HexOH, in alcothermal conditions (300 °C, 24.5 MPa) over CeO(2) nanocrystals (NCs) size, morphology, and surface properties was investigated. The crystallite size of the CeO(2) nanocrystals can be tuned in the range 3-7 nm depending on the considered alcohol, and their surface has been modified by these solvents without the use of surfactants. Mechanisms are proposed for the interaction of primary and secondary alcohols with CeO(2) surface and its functionalization during the synthesis based on FTIR and TGA-MS studies. This study allows apprehending the role of alcohols during the synthesis and may lead to an informed choice of solvent as a function of the required size and surface properties of CeO(2) NCs. It also opens new route to CeO(2) functionalization using supercritical alcohol derivatives.
Publication
(16671898; CEO; 10.1111/j.1442-9071.2006.01194.x)
Journal: Clinical and Experimental Ophthalmology
June/18/2006
Abstract
On the 65th anniversary of Gregg's observation "Congenital cataract following German measles in the mother", rubella has retired as the leading cause of congenital cataract, from 87% of Gregg's cohort to less than 3% over the last 25 years and almost zero now in Australia and other developed countries. However, people must keep vigilance in maintaining immunization rates and encourage immunization in developing countries. At least one-fifth of congenital cataract is familial. Understanding the genetics of familial cataract will lead to better treatment of congenital as well as age-related cataract.
Publication
Journal: Health Affairs
July/4/2007
Abstract
John Brown, current chairman and past chief executive officer (CEO) of the Stryker Corporation, reviews the development of his device firm and the medical device industry over the past thirty years. Brown describes the trajectory of innovation in medical devices and the managerial and organizational strategy he pioneered at Stryker to achieve consistently high growth rates over the long term. He also shares his perspective on some of the current policy issues facing the device industry today, including product safety, conflicts of interest, rising product prices, and direct-to-consumer advertising.
Authors
Publication
Journal: Biochimica et Biophysica Acta - General Subjects
December/14/2015
Abstract
BACKGROUND
Some reports indicate that NPs are ingested by cells via different mechanisms, including phagocytosis. In contrast, the direct role of NPs on the phagocytic process is not well documented. The aim of this study was to determine if titanium dioxide (TiO(2)), zinc oxide (ZnO) and cerium dioxide (CeO(2)) NPs, could alter the ability of neutrophils to exert phagocytosis.
METHODS
Freshly isolated human neutrophils were incubated with NPs and their ability to phagocytose opsonized sheep red blood cells (SRBCs) or fluorescent latex beads (LBs) was assessed by optical and fluorescence microscopy, respectively. Syk activation was assessed by western blot experiments and a pharmacological approach with piceatannol, a Syk inhibitor, was used to determine its role in NPs-induced neutrophils. The cytokine granulocyte macrophage-colony stimulating factor (GM-CSF) was used as a positive control.
RESULTS
All tested NPs enhanced the ability of neutrophil to phagocytose SRBCs and LBs. Syk was activated in NPs-induced neutrophils as evidenced by its increased tyrosine phosphorylation level vs controls and the ability of NPs-induced phagocytosis was reversed by piceatannol.
CONCLUSIONS
We found that the tested NPs enhanced phagocytosis, although at different degree, and this occurred by a Syk-dependent mechanism.
CONCLUSIONS
This is the first study demonstrating that NPs, by themselves, can directly enhance FcR-mediated (opsonized SRBCs) and complement-mediated (LBs) phagocytosis. Moreover, as part of their mode of action, we determined that NPs can act similarly to GM-CSF leading to Syk activation involved in phagocytosis. This has to be taken under consideration for future nanobiology and nanomedicine studies.
Publication
Journal: Biosensors and Bioelectronics
October/19/2016
Abstract
In the present work, an ultrasensitive sandwich-type electrochemical immunosensor based on a novel signal amplification strategy was designed for quantitative detection of alpha fetoprotein (AFP). Au nanoparticles with biocompatibility were electrodeposited on the surface of glassy carbon electrode (GCE) which can effectively capture and immobilize primary anti-AFP (Ab1) to significantly amplify the electrochemical signal. Graphene Oxide and CeO2 mesoporous nanocomposite functionalized by the 3-aminopropyltriethoxysilane supported Pd octahedral nanoparticles (Pd/APTES-M-CeO2-GS) were utilized as labels of detection anti-AFP (Ab2). Pd octahedral nanoparticles presented good catalytic activity towards the reduction of H2O2. Due to the large specific surface area and good adsorption properties of APTES-CeO2-GS nanocomposite, large amount of Pd octahedral nanoparticles could be immobilized, which could amplify the electrochemical signal and improve the sensitivity of the immunosensor. Under optimal conditions, the immunosensor exhibited wide linear range from 0.1 pg/mL to 50 ng/mL with a low detection limit of 0.033 pg/mL (S/N=3) for AFP detection. In addition, high sensitivity, excellent selectivity, good reproducibility and stability were obtained for the immunosensor, which has a promising application for quantitative detection of other tumor markers in clinical diagnosis.
Publication
Journal: Environmental Science & Technology
January/21/2013
Abstract
The amorphous Ce-Ti mixed oxides were reported to be catalysts for selective catalytic reduction of NO(x) with NH(3), in which Ce and not Ti acts as their solvent in spite of the fact that Ce is low in content. The amorphous catalysts were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) equipped with selective area electron diffraction (SAED). The Ce-Ti amorphous oxide shows higher activity than its crystalline counterpart at lower temperatures. Moreover, the presence of small CeO(2) crystallites as for the impregnated sample is deleterious to activity. The Ce-O-Ti short-range order species with the interaction between Ce and Ti in atomic scale was confirmed for the first time to be the active site using temperature programmed reduction with H(2) (H(2)-TPR), in situ FTIR spectra of NO adsorption, X-ray photoelectron spectroscopy (XPS), and X-ray absorption fine-structure (XAFS). Lastly, the Ce-O-Ti structure was directly observed by field-emission TEM (FETEM).
Publication
Journal: Journal of Hazardous Materials
March/26/2007
Abstract
The paper demonstrates that the photocatalytic activity of TiO(2) towards the decomposition of gaseous benzene in a batch reactor can be greatly improved by loading TiO(2) on the surface of Sr(2)CeO(4). The research investigates the optimum loading amount of TiO(2) on Sr(2)CeO(4) in enhancing the photocatalytic activity of TiO(2). The prepared photocatalyst was characterized by XRD, UV-vis diffuse reflectance and XPS analyses. TiO(2) is loaded on Sr(2)CeO(4) at 773K. TiO(2)/Sr(2)CeO(4) absorbs much more visible light than TiO(2). The XPS spectrum shows that there are Ti, O, C, Sr elements on the surface of the TiO(2)/Sr(2)CeO(4), and that the binding energy value of Ti2p transfers to a lower value. TiO(2)/Sr(2)CeO(4) demonstrates 2.0 times the photocatalytic activity of pure TiO(2). Based upon these observations, the mechanistic role of Sr(2)CeO(4) in the photocatalytic oxidation reaction has been suggested.
Publication
Journal: Journal of the American Chemical Society
November/8/2004
Abstract
A series of alpha,omega-bis donor substituted oligophenylenevinylene dimers held together by the [2.2]paracyclophane core were synthesized to probe how the number of repeat units and through-space delocalization influence two-photon absorption cross sections. Specifically, the paracyclophane molecules are tetra(4,7,12,15)-(4'-dihexylaminostyryl)[2.2]paracyclophane (3R(D)), tetra(4,7,12,15)-(4' '-(4'-dihexylaminostyryl)styryl)[2.2]paracyclophane (5R(D)), and tetra(4,7,12,15)-(4' "-(4' '-(4'-dihexylaminostyryl)styryl)styryl)[2.2]paracyclophane (7R(D)). The compounds bis(1,4)-(4'-dihexylaminostyryl)benzene (3R) and bis(1,4)-(4' '-(4'-dihexylaminostyryl)styryl)benzene (5R) were also synthesized to reveal the properties of the "monomeric" counterparts. The two-photon absorption cross sections were determined by the two-photon induced fluorescence method using both femtosecond and nanosecond pulsed lasers as excitation sources. While there is a red shift in the linear absorption spectra when going from the "monomer" chromophore to the paracyclophane "dimer" (i.e., 3R ->> 3R(D), 5R ->> 5R(D)), there is no shift in the two-photon absorption maxima. A theoretical treatment of these trends and the dependence of transition dipole moments on molecular structure rely on calculations that interfaced time-dependent density functional theory (TDDFT) techniques with the collective electronic oscillator (CEO) program. These theoretical and experimental results indicate that intermolecular interactions can strongly affect B(u) states but weakly perturb A(g) states, due to the small dipole-dipole coupling between A(g) states on the chromophores in the dimer.
Publication
(16451250; CEO; 10.1111/j.1442-9071.2006.01164.x)
Journal: Clinical and Experimental Ophthalmology
May/7/2006
Publication
(16451265; CEO; 10.1111/j.1442-9071.2006.01152.x)
Journal: Clinical and Experimental Ophthalmology
May/7/2006
Abstract
Two patients, both with a history of major depressive disorder, presented with large bilateral corneal epithelial defects and ring-shaped stromal opacities. Both were initially treated unsuccessfully with topical antibiotic therapy for presumed infectious keratitis. One patient eventually admitted to topical anaesthetic abuse. In the second patient, signs of topical anaesthetic abuse and Munchausen's syndrome became evident. Cessation of anaesthetic use resulted in rapid resolution of the corneal epithelial defects in both patients. Anaesthetic abuse keratopathy is often a manifestation of underlying psychiatric illness, and psychiatric intervention is a very important part of management. To the authors' knowledge, this is the first report of ocular Munchausen's syndrome manifesting as anaesthetic abuse keratopathy.
Publication
Journal: Journal of Carcinogenesis
July/13/2011
Abstract
BACKGROUND
Recent epidemiologic evidence suggests that the common polymorphism at amino acid residue 399 of the x-ray cross complementing-1 (XRCC1) protein, a key component of the base excision repair (BER) pathway for DNA damage, plays a significant role in the genetic variability of individuals in terms of the mutagenic damage they experience following exposure to the carcinogen vinyl chloride (VC). The aim of this study was to provide support for the biological plausibility of these epidemiologic observations with experimental data derived from cell lines in culture from individuals who were either homozygous wild-type or homozygous variant for this XRCC1 polymorphism following exposure to chloroethylene oxide (CEO), the active metabolite of VC, with measurement of the induced etheno-DNA adducts before and after repair.
METHODS
Immortalized lymphoblast cell lines from seven VC workers (four homozygous wild-type and three homozygous variant for the 399 XRCC1 polymorphism) were exposed to CEO, and etheno-adenosine (epsilonA) adduct levels were determined by enzyme-linked immunosorbent assay (ELISA) pre-exposure and at 0, 4, 8 and 24 h following exposure.
RESULTS
The average epsilonA adduct levels were statistically significantly higher in the variant cells compared to the wild-type cells at 8 and 24 h following exposure (P Conclusion: These results are consistent with the epidemiologic findings of the types of VC-induced biomarkers observed in exposed individuals and the mutational spectra found in the resultant tumors as well as the key role that BER, especially XRCC1, plays in this carcinogenic pathway.
Publication
Journal: Environmental Science & Technology
October/11/2012
Abstract
The deposition behavior of cerium dioxide (CeO(2)) nanoparticles (NPs) in dilute NaCl solutions was investigated as a function of collector surface composition, pH, ionic strength, and organic matter (OM). Sensors coated separately with silica, iron oxide, and alumina were applied in quartz crystal microbalance with dissipation (QCM-D) to examine the effect of these mineral phases on CeO(2) deposition in NaCl solution (1-200 mM). Frequency and dissipation shift followed the order: silica>> iron oxide>> alumina in 10 mM NaCl at pH 4.0. No significant deposition was observed at pH 6.0 and 8.5 on any of the tested sensors. However, ≥ 94.3% of CeO(2) NPs deposited onto Ottawa sand in columns in 10 mM NaCl at pH 6.0 and 8.5. The inconsistency in the different experimental approaches can be mainly attributed to NP aggregation, surface heterogeneity of Ottawa sand, and flow geometry. In QCM-D experiments, the deposition kinetics was found to be qualitatively consistent with the predictions based on the classical colloidal stability theory. The presence of low levels (1-6 mg/L) of Suwannee River humic acid, fulvic acid, alginate, citric acid, and carboxymethyl cellulose greatly enhanced the stability and mobility of CeO(2) NPs in 1 mM NaCl at pH 6.5. The poor correlation between the transport behavior and electrophoretic mobility of CeO(2) NPs implies that the electrosteric effect of OM was involved.
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