The interactions between pharmaceuticals and nanomaterials and its potentially resulting toxicological effects in living systems are only insufficiently investigated. In this study, two model compounds, acetaminophen, a pharmaceutical, and cerium dioxide, a manufactured nanomaterial, were investigated in combination and individually. Upon inhalation, cerium dioxide nanomaterials were shown to systemically translocate into other organs, such as the liver. Therefore we picked the human liver cell line HuH-7 cells as an in vitro system to investigate liver toxicity. Possible synergistic or antagonistic metabolic changes after co-exposure scenarios were investigated. Toxicological data of the water soluble tetrazolium (WST-1) assay for cell proliferation and genotoxicity assessment using the Comet assay were combined with an untargeted as well as a targeted lipidomics approach. We found an attenuated cytotoxicity and an altered metabolic profile in co-exposure experiments with cerium dioxide, indicating an interaction of both compounds at these endpoints. Single exposure against cerium dioxide showed a genotoxic effect in the Comet assay. Conversely, acetaminophen exhibited no genotoxic effect. Comet assay data do not indicate an enhancement of genotoxicity after co-exposure. The results obtained in this study highlight the advantage of investigating co-exposure scenarios, especially for bioactive substances.

Cerium (Ce), the most abundant of rare earth elements in the earth\'s crust, has received much health concerns due to its wide application in industry, agriculture, and medicine. The current study aims to evaluate whether there is an association between Ce exposures and the risk of developing oral cancer. Serum Ce level of 324 oral cancer patients and 650 matched healthy controls were measured by inductively coupled plasma mass spectrometry. Association between Ce level and the risk of oral cancer was estimated with an unconditional logistic regression model. Serum Ce concentrations in the oral cancer patients and controls were 0.57 (0.21-3.02) μg/L and 2.27 (0.72-4.26) μg/L, respectively. High level of Ce was associated with a decreased risk of oral cancer (OR: 0.60, 95% CI: 0.43-0.84). Stronger inverse associations between high level of Ce and oral cancer risk were observed among those with smoking (OR: 0.46, 95% CI: 0.27-0.79), drinking (OR: 0.50, 95% CI: 0.26-0.96), limited intake of leafy vegetables (OR: 0.40, 95% CI: 0.22-0.71) and fish (OR: 0.52, 95% CI: 0.33-0.83). There were significant multiplicative interactions between Ce level and alcohol drinking or intake of leafy vegetables and fish (all Pinteraction <0.05). This preliminary case-control study suggests an inverse association between high serum Ce level and the risk of oral cancer. Further prospective studies with a larger sample size are needed to confirm the findings.

High concentration of orthophosphate ion (OP) in anaerobically digested sludge can lead to struvite crystallization, deterioration of sludge dewaterability, and elevated mainstream OP loading through centrate recirculation. The Upper Occoquan Service Authority (UOSA) has observed seasonally high OP levels in its dewatering blend tank, which was found in this study to be a consequence of unwanted biological phosphorus accumulation during the intensified winter denitrification operation and the subsequent OP release in the course of anaerobic digestion. In order to control the nuisance struvite scaling issues, a bench study was conducted and cerium chloride (CeCl3 ) was dosed as an effective OP precipitant. The results of this study demonstrated that CeCl3 dosing showed higher OP removal efficiency than other commonly used OP precipitants. In addition, bench-scale simulations indicated sludge dewaterability improvements which were used to predict lower polymer and dewatering energy demands at the full scale. The economic analysis conducted in this case study showed that the seasonal dosing of CeCl3 at UOSA has the potential to provide a net annual saving of US $47,000. PRACTITIONER POINTS: Biological phosphorus accumulation during the intensified denitrification operation caused seasonally high sludge OP and struvite scaling issues at UOSA. CeCl3 was evaluated as an effective OP precipitant for struvite control and dewaterability improvement when aluminum and iron were determined to be unfavorable. Seasonal dosing of CeCl3 at UOSA projected a net annual saving of US $47,000.

Wound healing in diabetes is frequently impaired and its treatment remains a challenge. The ability of topical application of cerium (Ce) dioxide nanoparticles (CNPs) to accelerate wound healing in an animal model provides a rationale to develop this technology for use in humans affected by traumatic injury, diabetes and burns. We first described a case report of successful topical treatment of neuropathic diabetic foot ulcers with novel gel containing CNPs. The CNPs has bacteriostatic activity, anti-inflammatory properties and can penetrated into the wound tissue and reduced oxidative damage therefore protect regenerative tissue, suggesting a therapeutic potential for topical treatment of diabetic foot ulcers.

The influence of nanocrystalline cerium dioxide (NCD, 1 and 100 mg/kg per os daily for 10 days) on morphofuctional state of reproductive system was investigated in ageing male rats. It has been established that activation of hormone-producing testicular Leydig\'s cells, as well as of secretory and proliferative processes in prostate, underlies the stimulating effect of NCD at a dose 1 mg/kg on hormonal function of testis and spermatogenesis of ageing male rats. NCD used at a dose 100 mg/kg had no significant effect on the assessed indices of morphofuctional state of reproductive system.

We propose a resolution to the puzzle presented by the surface defects observed with STM at the (111) surface facet of CeO 2 single crystals. In the seminal paper of Esch et al. [Science 309, 752 (2005)] they were identified with oxygen vacancies, but the observed behavior of these defects is inconsistent with the results of density functional theory (DFT) studies of oxygen vacancies in the literature. We resolve these inconsistencies via DFT calculations of the properties of both oxygen vacancies and fluorine impurities at CeO2(111), the latter having recently been shown to exist in high concentrations in single crystals from a widely used commercial source of such samples. We find that the simulated filled-state STM images of surface-layer oxygen vacancies and fluorine impurities are essentially identical, which would render problematic their experimental distinction by such images alone. However, we find that our theoretical results for the most stable location, mobility, and tendency to cluster, of fluorine impurities are consistent with experimental observations, in contrast to those for oxygen vacancies. Based on these results, we propose that the surface defects observed in STM experiments on CeO2 single crystals reported heretofore were not oxygen vacancies, but fluorine impurities. Since the similarity of the simulated STM images of the two defects is due primarily to the relative energies of the 2p states of oxygen and fluorine ions, this confusion might also occur for other oxides which have been either doped or contaminated with fluorine.

暂无摘要。

OBJECTIVE: To examine the clinical performance of veneered ceria-stabilized tetragonal zirconia/alumina-nanocomposite (Ce-TZP/A-nanocomposite) frameworks for three-unit fixed dental prostheses (FDPs).
METHODS: Eight patients in need of one FDP replacing one premolar or molar were included in this case series. Eight Ce-TZP/A-nanocomposite FDP frameworks were fabricated with a CAD/CAM system (Hint-Els) and veneered with a zirconia veneering ceramic (Vintage ZR, Shofu). The FDPs were cemented with resin cement (baseline) and were evaluated at baseline; 2 weeks; and 3, 6, and 12 months after cementation. For the technical evaluation, the USPHS criteria were used. The biologic outcome was judged by comparing the plaque control record (PCR), bleeding on probing (BOP), and probing pocket depth (PPD) of the abutment teeth (test) and untreated contralateral teeth (control). Radiographs were made at baseline and at 6 and 12 months of follow-up. The data were descriptively analyzed.
RESULTS: The mean observation period of the eight examined FDPs was 12.8 +/- 1.1 months. The survival rate of the FDPs was 100%. Furthermore, no technical or biologic complications were found. No differences of the mean (m) PCR (test: 0.1 +/- 0.1, control: 0.2 +/- 0.2), mBOP (test: 0.2 +/- 0.2, control: 0.1 +/- 0.1), and mPPD (test: 2.6 +/- 0.8, control: 2.6 +/- 0.6) were found between test and control teeth.
CONCLUSIONS: Ce-TZP/A nanocomposite was found to be a reliable framework material at 1 year of function. Longer observation periods and randomized controlled clinical trials including more patients are needed to validate these findings.

Envirox is a scientifically and commercially proven diesel fuel combustion catalyst based on nanoparticulate cerium oxide and has been demonstrated to reduce fuel consumption, greenhouse gas emissions (CO(2)), and particulate emissions when added to diesel at levels of 5 mg/L. Studies have confirmed the adverse effects of particulates on respiratory and cardiac health, and while the use of Envirox contributes to a reduction in the particulate content in the air, it is necessary to demonstrate that the addition of Envirox does not alter the intrinsic toxicity of particles emitted in the exhaust. The purpose of this study was to evaluate the safety in use of Envirox by addressing the classical risk paradigm. Hazard assessment has been addressed by examining a range of in vitro cell and cell-free endpoints to assess the toxicity of cerium oxide nanoparticles as well as particulates emitted from engines using Envirox. Exposure assessment has taken data from modeling studies and from airborne monitoring sites in London and Newcastle adjacent to routes where vehicles using Envirox passed. Data have demonstrated that for the exposure levels measured, the estimated internal dose for a referential human in a chronic exposure situation is much lower than the no-observed-effect level (NOEL) in the in vitro toxicity studies. Exposure to nano-size cerium oxide as a result of the addition of Envirox to diesel fuel at the current levels of exposure in ambient air is therefore unlikely to lead to pulmonary oxidative stress and inflammation, which are the precursors for respiratory and cardiac health problems.

The AC impedance response of mixed ionic and electronic conductors (MIECs) exposed to a chemical potential gradient is derived from first principles. In such a system, the chemical potential gradient induces a gradient in the carrier concentration. For the particular system considered, 15% samarium doped ceria (SDC15) with Ba(0.5)Sr(0.5)Co(0.8)Fe(0.2)O(3-delta) (BSCF) and Pt electrodes, the oxygen vacancy concentration is a constant under the experimental conditions and it is the electron concentration that varies. The resulting equations are mapped to an equivalent circuit that bears some resemblance to recently discussed equivalent circuit models for MIECs under uniform chemical potential conditions, but differs in that active elements, specifically, voltage-controlled current sources, occur. It is shown that from a combination of open circuit voltage measurements and AC impedance spectroscopy, it is possible to use this model to determine the oxygen partial pressure drop that occurs between the gas phase in the electrode chambers and the electrode|electrolyte interface, as well as the interfacial polarization resistance. As discussed in detail, this resistance corresponds to the slope of the interfacial polarization curve. Measurements were carried out at temperatures between 550 and 650 degrees C and oxygen partial pressure at the Pt anode ranging from 10(-29) to 10(-24) atm (attained using H(2)/H(2)O/Ar mixtures), while the cathode was exposed to either synthetic air or neat oxygen. The oxygen partial pressure drop at the anode was typically about five orders of magnitude, whereas that at the cathode was about 0.1 atm for measurements using air. Accordingly, the poor activity of the anode is responsible for a loss in open circuit voltage of about 0.22 V, whereas the cathode is responsible for only about 0.01 V, reflecting the high activity of BSCF for oxygen electro-reduction. The interfacial polarization resistance at the anode displayed dependences on oxygen partial pressure and on temperature that mimic those of the electronic resistivity of SDC15. This behavior is consistent with hydrogen electro-oxidation occurring directly on the ceria surface and electron migration being the rate-limiting step. However, the equivalent resistance implied by the oxygen partial pressure drop across the anode displayed slightly different behavior, possibly indicative of a more complex reaction pathway.