Oxidative Stress in the Liver of Mice Caused by Intraperitoneal Injection with Lanthanoides

In order to study the mechanisms underlying the effects of lanthanoid (Ln) on the liver, ICR mice were injected with LaCl₃, CeCl₃, and NdCl₃ at a dose of 20 mg/kg BW into the abdominal cavity daily for 14 days. We then examined oxidative stress-mediated responses in the liver. The increase of lipid peroxide in the liver produced by Ln suggested an oxidative attack that was activated by a reduction of antioxidative defense mechanisms as measured by analyzing the activities of superoxide dismutase, catalase, and ascorbate peroxidase, as well as antioxidant levels such as glutathione and ascorbic acid, which were greatest in Ce³⁺ treatment, medium in Nd³⁺, and least in La³⁺. Our results also implied that the oxidative stress in the liver caused by Ln likely is Ce³⁺ > Nd³⁺ >La³⁺, but the mechanisms need to be further studied in future.     

Oxidative Injury in the Brain of mice Caused by Lanthanid

The organ toxicity of lanthanides (Ln) on organisms had been recognized, but very little is known about the oxidative injury of brain caused by Ln. In order to study the mechanisms underlying the effects of Ln on the brain, ICR mice were injected with a single 20 mg/kg body weight dose of LaCl₃, CeCl₃, and NdCl₃ into the abdominal cavity daily for 14 days. We then examined the coefficient of the brain, the brain pathological changes and oxidative stress-mediated responses, and the accumulation of Ln and levels of neurochemicals in the brain. The results showed that CeCl₃ and NdCl₃ could induce some neurons to turn inflammatory cells and slight edema but did not observe the brain pathological changes from LaCl₃-treated group. The concentrations of La, Ce, and Nd in the brain were significantly different and ranked in the order of Ce, Nd, and La. The injury of the brain and oxidative stress occurred as Ln appeared to trigger a cascade of reactions such as lipid peroxidation, the decreases of the total antioxidation capacity and activities of antioxidative enzymes, the excessive release of nitric oxide, the increase of glutamic acid, and the downregulated level of acetylcholinesterase activities. Furthermore, both Ce³⁺ and Nd³⁺ exhibited higher oxidative stress and toxicity on brain than La³⁺, and Ce³⁺ caused more severe brain injuries and oxidative stress than Nd³⁺, implying that the differences in the brain injuries caused by Ln might be related to the number of 4f electrons of Ln.     

Luminescent CeCl3 nanoparticles by Tris(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)cerium diglyme photolysis in chlorinated solvents

Irradiation of [Ce(hfac)₃(diglyme)] (hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato and diglyme (DG) = 2,5,8,11,14-pentaoxapentadecane) in chlorinated solvents (CH₂Cl₂, CCl₄) with UV light led to luminescent colloidal CeCl₃ that was characterized by transmission electron microscopy (TEM) analysis. When a substrate, quartz or silicon was present in the reaction cell, photoluminescent films were obtained, containing either pure CeCl₃ or mixtures of CeCl₃, CeF₃ and CeOx in function of the experimental parameters of irradiation. Nanostructured and luminescent pure CeCl₃ films were obtained by irradiation of the cerium complex in CCl₄ at high intensity light for a few minutes. The films were characterized by X-ray diffraction (XRD), Energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), TEM, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The kinetics of the [Ce(hfac)₃(diglyme)] solution photodegradation, followed by UV spectrophotometry and spectrofluorimetry, pointed to CeCl₃ formation by a solvent-initiated reaction, whereas the other inorganic compounds were the products of side reactions.     

Optical and structural properties of composites films based on Ce3+-doped yttrium aluminium garnet nanoparticles embedded in polystyrene

In the present work, attempts have been made to prepare scintillating nanoparticle composite films of Ce³⁺-doped Y₃Al₅O₁₂ (YAG:Ce) embedded in a polystyrene (PS) polymer. A YAG:Ce phosphor has been previously synthesized using the sol–gel method. YAG:Ce-PS composite films of 250 ± 30 μm thickness were prepared using a solvent casting procedure with different PS/solvent concentration and a different mass ratio between nanoparticles of YAG:Ce and PS. X-ray diffraction analysis confirmed that the YAG:Ce powders were successfully prepared. Using thermogravimetric analyses and differential scanning calorimetry, we found that the glass transition temperature (Tg) and thermal degradation were shifted to higher temperatures for composite films relative to pure PS. Photoluminescence showed the yellow emission of the Ce³⁺-doped YAG phosphors, which was attributed to the 5d→4f transition of Ce³⁺ ion and the intensity of the emissions changed with the mass ratio of the YAG:Ce nanoparticles incorporated in the polymer and with the concentration of the polymer solution.     

Photoluminescence of Dy3+ activator sensitized by Ce3+ in KNaSO4 microphosphor

The KNaSO₄ microphosphor doped with Ce or Ce and Dy prepared by a wet chemical method was studied by scanning electron microscopy (SEM) and characterized by photoluminescence (PL). KNaSO₄ has a 5‐µm particle size detected by SEM. The KNaSO₄:Ce³⁺ spectrum shows a single emission band at 327 nm for an excitation of 269 nm due to 5d → 4f transition of the Ce³⁺ ion, indicating weak spin orbiting coupling of the Ce³⁺ ground state. Efficient energy transfer takes place from Ce³⁺ → Dy³⁺ sublattices indicating that Ce³⁺ could effectively sensitize Dy³⁺ (orange emission) and that the Ce³⁺ emission weakens significantly in KNaSO₄. The powder form of prepared KNaSO₄ show negligible change in morphologies and hence no effect on the particle size. The characteristics of this powder could provide improved luminescence properties. The development and understanding of this photoluminescence and the effect of Dy³⁺ on KNaSO₄: Ce³⁺ are discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

The Effects of Lanthanoid on the Structure–Function of Lactate Dehydrogenase from Mice Heart

The activity of lactate dehydrogenase (LDH, EC1.1.1.27) is often changed upon inflammatory responses in animals. Lanthanoid (Ln) was shown to provoke various inflammatory responses both in rats and mice; however, the molecular mechanism by which Ln³⁺ exert its toxicity has not been completely understood, especially that we know little about the mechanism of the interaction between Ln with 4f electron shell and alternation valence and LDH. In this report, we investigated the mechanisms of LaCl₃, CeCl₃, and NdCl₃ on LDH activity in vivo and in vitro. Our results showed that La³⁺, Ce³⁺, and Nd³⁺ could significantly activate LDH in vivo and in vitro; the order of activation was Ce³⁺?>?Nd³⁺?>?La³⁺?>?control. The affinity of LDH for Ce³⁺ was higher than Nd³⁺ and La³⁺; the saturated binding sites for Ce³⁺ on the LDH protein were 1.2 and for La³⁺ and Nd³⁺ 1.55. Ln³⁺ caused the reduction of exposure degree of cysteine or tryptophan/tyrosine of LDH, the increase of space resistance, and the enhancement of α-helix in secondary structure of LDH, which was greatest in Ce³⁺ treatment, medium in Nd³⁺ treatment, and least in La³⁺ treatment. It implied that the changes of structure–function on LDH caused by Ln³⁺ were closely related to the characteristics of 4f electron shell and alternation valence in Ln.     

The Mechanism of CeCl<Subscript>3</Subscript> on the Activiation of Alanine Aminotransferase from Mice

The activity of alanine aminotransferase (ALT; E.C. 2.6.1.2) is often changed upon inflammatory responses in animals. Rare earths was shown to provoke various inflammatory responses both in rats and mice; however, the molecular mechanism by which rare earths exert its toxicity has not been completely understood, especially, we know little about the mechanism of the interaction between CeCl₃ and ALT. In this report, we investigated the mechanisms of CeCl₃ on ALT activity in vivo and in vitro. Our results showed that Ce³⁺ could significantly activate ALT in vivo and in vitro; the kinetics constant (Km) and Vmax were 0.018 μM and 1,380 unit mg⁻¹ protein min⁻¹, respectively, at a low concentration of Ce³⁺, and 0.027 μM and 624 unit mg⁻¹ protein min⁻¹, respectively, at a high concentration of Ce³⁺. By UV absorption and fluorescence spectroscopy assays, the Ce³⁺ was determined to be directly bound to ALT; the binding site of Ce³⁺ to ALT was 1.72, and the binding constants of the binding site were 4.82 × 10⁸ and 9.05 × 10⁷ L mol⁻¹. Based on the analysis of the circular dichroism spectra, it was concluded that the binding of Ce³⁺ altered the secondary structure of ALT, suggesting that the observed enhancement of ALT activity was caused by a subtle structural change in the active site through the formation of the complex with Ce³⁺.     

Changes in Liver Cell DNA Methylation Status in Diabetic Mice Affect Its FT-IR Characteristics

Background

Lower levels of cytosine methylation have been found in the liver cell DNA from non-obese diabetic (NOD) mice under hyperglycemic conditions. Because the Fourier transform-infrared (FT-IR) profiles of dry DNA samples are differently affected by DNA base composition, single-stranded form and histone binding, it is expected that the methylation status in the DNA could also affect its FT-IR profile.

Methodology/Principal Findings

The DNA FT-IR signatures obtained from the liver cell nuclei of hyperglycemic and normoglycemic NOD mice of the same age were compared. Dried DNA samples were examined in an IR microspectroscope equipped with an all-reflecting objective (ARO) and adequate software.

Conclusions/Significance

Changes in DNA cytosine methylation levels induced by hyperglycemia in mouse liver cells produced changes in the respective DNA FT-IR profiles, revealing modifications to the vibrational intensities and frequencies of several chemical markers, including ν_as –CH₃ stretching vibrations in the 5-methylcytosine methyl group. A smaller band area reflecting lower energy absorbed in the DNA was found in the hyperglycemic mice and assumed to be related to the lower levels of –CH₃ groups. Other spectral differences were found at 1700–1500 cm⁻¹ and in the fingerprint region, and a slight change in the DNA conformation at the lower DNA methylation levels was suggested for the hyperglycemic mice. The changes that affect cytosine methylation levels certainly affect the DNA-protein interactions and, consequently, gene expression in liver cells from the hyperglycemic NOD mice.     

Signal role for activation of caspase-3-like protease and burst of superoxide anions during Ce<Superscript>4+</Superscript>-induced apoptosis of cultured <Emphasis Type="Italic">Taxus cuspidata</Emphasis> cells

The signal events of 1 mM Ce⁴⁺ (Ce(NH₄)₂(NO₃)₆)-induced apoptosis of cultured Taxus cuspidata cells were investigated. The percentage of apoptotic cells increased from 0.82% to 51.32% within 6 days. Caspase-3-like protease activity became notable during the second day of Ce⁴⁺-treatment, and the maximum activity was 5-fold higher than that of control cells at the fourth day. When the experiment system was pretreated with acetyl-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO) at 100 M, caspase-3-like activity resulted in distinct inhibition by 70% and 77.3% after 3 and 4 days of induction. Furthermore, 100 M Ac-DEVD-CHO partially reduced the apoptotic cells by 58.6% and 60.8% at day 4 and 5 respectively. Ce⁴⁺ induced superoxide anions (O₂·–) transient burst, and the first peak appeared at around 3.7–4 h, the second appeared at about 7 h. Both O₂·– burst and cell apoptosis were effectively suppressed by application of diphenyl iodonium (NADPH oxidase inhibitor). Inhibition of O₂·– production attenuated caspase-3-like activation by 49% and 53.6% during day 3 and 4 respectively. In addition, a total of 15 protein spots changed in response to caspase-3-like protease activation were identified by two-dimensional gel electrophoresis. These results suggest that Ce⁴⁺ of 1 mM induces apoptosis in suspension cultures of T. cuspidata through O₂·– burst as well as caspase-3-like protease activation. The burst of O₂·– exerts its activity as an upstream of caspase-3-like activation. Our results also implicate that other signal pathways independent of an O₂·– burst possibly participate in mediating caspase-3-like protease activation.     

Crystal structure of Ce(IV)/dipicolinate complex as catalyst for DNA hydrolysis

The structures of Ce⁴⁺ complexes that are active for DNA hydrolysis were determined for the first time by X-ray crystallography. The crystals were prepared from a 1:2 mixture of Ce(NH₄)₂(NO₃)₆ and dipicolinic acid (2,6-pyridinedicarboxylic acid). Depending on the recrystallization conditions, three types of crystals were obtained. Some of the Ce⁴⁺ ions in these complexes have enough coordinated water molecules that can directly and indirectly participate in the catalysis. The distances between the Ce⁴⁺ and the dipicolinate ligand are considerably shorter than those in the corresponding La³⁺ and Ce³⁺ complexes. On the other hand, the distances between the Ce⁴⁺ and its coordinated water are similar to those for the La³⁺ and Ce³⁺ complexes. In a proposed mechanism of DNA hydrolysis, the scissile phosphodiester linkage is notably activated by coordination to Ce⁴⁺ and attacked by the Ce⁴⁺-bound hydroxide. The process is further assisted by acid catalysis of Ce⁴⁺-bound water. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Probing the optical properties and luminescence mechanism of a UV‐emitting SrBPO5:Ce3+ phosphor

Ce‐doped (1 × 10^?5 to 3.0 mol%) SrBPO₅ phosphors were synthesized using a conventional solid‐state reaction route at 1273 K in an air atmosphere. Phase and morphology of the samples were studied from powder X‐ray diffraction (XRD) patterns and scanning electron microscope (SEM) micrographs, respectively. The band gap energies of the pure and Ce‐doped SrBPO₅ phosphors were calculated from the recorded diffuse reflectance spectra. Photoluminescence (PL) and Ce³⁺ lifetime were recorded at 300 and 77 K. Photoluminescence lifetime measurements revealed two‐lifetime values for Ce³⁺ at both 300 K (17 and 36 nsec) and 77 K (12 and 30 nsec), suggesting the presence of two different environments around Ce³⁺. Time‐resolved emission spectroscopy (TRES) studies confirmed the presence of Ce³⁺ in two different environments. In addition, SrBPO₅:Ce exhibited intense UV emission, signifying its possible use as an efficient sensitizer for solid‐state lighting applications. The effect of γ‐irradiation on PL was also determined. Thermally stimulated luminescence (TSL) glow curves of the γ‐irradiated phosphor, along with trap parameters, dose–response, and the possible TSL mechanism were also investigated. Positron annihilation lifetime spectroscopy was carried out to probe defects present in undoped and Ce‐doped SrBPO₅.     

Energy transfer between Ce3+ → Gd3+ or Tb3+ in KNaSO4 microphosphor

KNaSO₄ microphosphor doped with Ce,Gd and Ce,Tb and prepared by a wet chemical method was studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) characterization. KNaSO₄ has a 5‐µm particle size detected by SEM. KNaSO₄:Ce³⁺,Tb³⁺ showed blue and green emission (at 494 nm, 557 nm, 590 nm) of Tb³⁺ due to ⁵D₄ → ⁷F_J (J = 4, 5, 6) transitions. KNaSO₄:Ce³⁺,Gd³⁺ showed luminescence in the ultraviolet (UV) light region at 314 nm for an excitation at 271 nm wavelength. It was observed that efficient energy transfer took place from Ce³⁺ → Gd³⁺ and Ce³⁺ → Tb³⁺ sublattices indicating that Ce³⁺ could effectively sensitize Gd³⁺ or Tb³⁺ (green emission). Ce³⁺ emission weakened and Gd³⁺ or Tb³⁺ enhanced the emission significantly in KNaSO₄. This paper discusses the development and understanding of photoluminescence and the effect of Tb³⁺ and Gd³⁺ on KNaSO₄:Ce³⁺. Copyright © 2015 John Wiley & Sons, Ltd.     

The Oxidative Damage in Lung of Mice Caused By Lanthanoide

This study was performed with the objective of assessing the antioxidant response of the lung of mice to different rare earths. LaCl₃, CeCl₃, and NdCl₃ at a higher dose of 20 mg/kg body weight were injected into the nasal cavity of ICR mice for consecutive 14 days, respectively. The increase of pulmonary lipids peroxide produced by Ln suggested an oxidative attack that was activated by a reduction of antioxidative defense mechanisms as measured by analyzing the activities of superoxide dismutase, catalase, ascorbate peroxidase, and total antioxidant capacity, as well as antioxidant levels such as glutathione and ascorbic acid, which were greatest in Ce³⁺ treatment, medium in Nd³⁺, and least in La³⁺. It implied that the antioxidative responses of lung may be involved in 4f shell and alternable valence properties of Ln-induced lung toxicity.     

Effects of Ce doping on the luminescent property of Ca3SiO4Cl2:Eu phosphor for green lighting

White light‐emitting diodes (LEDs) for green lighting are new solutions for energy saving and environmental protection. Ca₃SiO₄Cl₂:Ce,Eu is an efficient phosphor for white LEDs. Effective energy transfer from Ce³⁺ to Eu²⁺ occurs in Ca₃SiO₄Cl₂:Ce,Eu due to good spectrum overlap between the emission band of Ca₃SiO₄Cl₂:Ce and the excitation band of Ca₃SiO₄Cl₂:Eu, and hues vary systematically from blue to green at different Ce concentrations. A great improvement in the luminescent property of Ca₃SiO₄Cl₂:Eu has been observed on Ce³⁺ doping, which is attributed to energy transfer from Ce³⁺ to Eu²⁺ and an increase in the number of luminescent centers (Eu²⁺) on Ce doping. The optimal sample has a quantum efficiency of up to 75%, and can be an efficient green phosphor for white LEDs. Copyright © 2014 John Wiley & Sons, Ltd.     

Luminescence investigation of a cerium‐doped yttrium vanadate phosphor

Cerium (Ce³⁺)‐doped (1, 3, and 7 mol%) yttrium vanadate phosphors were prepared using a co‐precipitation technique. The structural and optical properties of the synthesized samples were studied using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HR‐TEM), optical absorption, and photoluminescence (PL) spectroscopy techniques. The tetragonal structure and the formation of the nanosized crystallites in the YVO₄:Ce phosphor were confirmed using XRD analysis. HR‐TEM morphology showed rod‐like nanoparticles of different sizes. Optical absorption spectra demonstrated strong absorption bands at 268 and 276 nm. PL spectra showed strong peaks at 546, 574, and 691 nm following excitation at 300 nm. The calculated CIE chromaticity coordinates demonstrated that YVO₄:Ce could be used as a novel phosphor for the development of light‐emitting diode lamps.     

Regulative mechanism of Ce3+ relieves DNA damage caused by Cd2+ in the kidney of silver crucian carp

The mechanism of Cd²⁺ on the DNA cleavage and Ce³⁺ on the DNA repair in the kidney of silver crucian carp (Carassius auratus gibelio) is investigated by agarose gel electrophoresis methods and assaying biochemical indexes. It proves that Cd²⁺ induces the classical laddering degradation of DNA in vivo, but DNA cleavage is repaired after injecting with a low Ce³⁺ concentration under various Cd²⁺ concentrations. The DNA cleavage caused by Cd²⁺ is the result of the activation of deoxyribonuclease (DNase) and accumulation of reactive oxygen species (ROS), and Cd²⁺ destroys the antioxidant system, which diminishes the activities of superoxide dismutase, catalase, and peroxidase, and the increase of the lipid peroxidation (LPO) level. However, Ce³⁺ could inhibit activation of Cd²⁺ on DNase activity, relieve inhibition of Cd²⁺ on activities of the antioxidant enzyme, and diminish ROS accumulation. The results show that Ce³⁺ could relieve the toxicity of Cd²⁺ to silver crucian carp.     

Morphology,Solid Structure and Antioxidant Activity in Vitro of Angelica sinensis Polysaccharide-Ce(IV)

Angelica Sinensis polysaccharide cerium (ASP−Ce) was prepared by Angelica Sinensis polysaccharide (ASP) and cerium ammonium nitrate (NH₄)₂Ce(NO₃)₆. and its morphology, and solid structure was investigated. The antioxidant activity of the ASP−Ce complex in vitro was evaluated. The antioxidant activity of ASP−Ce complex in vitro was evaluated by the scavenging activity of 2,2-diphenyl-1-picrylhyrazyl radical (DPPH), hydroxyl radical (⋅OH) and superoxide anion radical ( ⋅). The results showed that the ASP−Ce had the more ordered structure for inserting the Ce⁴⁺ into the polymer chain of ASP and there was little change in the conformation of the polysaccharide from Ce⁴⁺. Three free radical scavenging experiments proved that ASP−Ce had better antioxidant capacity than of ASP, especially on DPPH, and then on ⋅. The scavenging rate of ASP−Ce at 1.0 mg/mL on DPPH reached 71.6 %. Therefore, these results provide references for the further development and utilization of rare earth-polysaccharide.     

Angiotensin-Induced Changes in the Apparent Size of Rat Liver Angiotensin Receptors

Abstract

Angiotensin receptors from rat liver were labeled using four different ligands : (Sar¹-(³H)Tyr⁴)-Angiotensin II ((³H)SarAII); (Sar¹-(³H)Tyr⁴-IIe⁸) -Angiotensin II ((³H)SarIIeAII); (Sar¹-(¹²⁵I)Tyr⁴-(4′-N₃)Phe⁸)-Anglotensin II (IN₃AII); (Sar¹-(¹²⁵I)Tyr⁴-(4′N₃D-Phe)⁸)-Angiotensin II (IN₃DPheAII) (³H) SarAII and IN₃AII behaved like agonists and (³H) SarlleAII and IN₃DPheAII like antagonists. All four ligands labeled the same population of sites. The azido derivatives allowed covalent labeling of receptors with a high yield (about 40%). Membranes were solubilized by Triton X-100 under experimental conditions which ensured complete solubilization of the liganded receptors in a stable form (less than 40% dissociation after 20 h). The apparent size of liganded angiotensin receptors was determined by gel filtration on Ultrogel ACA-34 columns and by SDS gel electrophoresis (in the case of covalent labeling). The apparent Stokes radius of solubilized angiotensin receptors was different wether the receptor was labeled with an agonist (Stokes radius = 6.2 ± 0. 1 nm (6) after labeling with (³H) SarAII) or with an antagonist (Stokes radii of 5. 5 ± 0. 1 (7), and 5.6 ± 0.1 nm (4) after labeling with (³H) SarIIeAII and IN₃DPheAII respectively). After covalent labeling with IN₃All anglotensin receptors were eluted as a mixture of light and heavy forms. SDS gel electrophoresis revealed only one molecular entity of M_r 64,000. It is concluded that binding of an agonist to liver angiotensin receptors triggers or stabilizes an interaction with another membrane component Involved in the coupling of the receptor to its primary effector.     

Differences in Protein Patterns in Suspension Cultures of Taxus cuspidata Induced by Cerium

The changes in soluble proteins induced by Ce⁴⁺ were analyzed in suspension cultures of Taxus cuspidata using two-dimensional polyacrylamide gel electrophoresis. The ultrastructure of cells obviously changed at day 4 after addition of Ce⁴⁺. Large amount of nuclear DNA fragments of about 200 bp were observed. Thirteen protein spots were different between the cultures grown with and without Ce⁴⁺ at day 4 as well as at day 6 after addition of Ce⁴⁺. This revised version was published online in July 2006 with corrections to the Cover Date.