Detecting cadmium during ultrastructural characterization of hepatotoxicity.

BACKGROUND: The threat of cadmium (Cd), which is the cause of itai-itai disease in Japan, is still complicated and confusing, especially for digestive system, such as liver disease. One of the most keys of this problem is demonstrating that the hepatotoxicity is indeed induced by Cd. Therefore, we attempt detecting Cd at microscale during ultrastructural imaging of liver tissue. METHODS: 12 rats were divided randomly into two experimental groups: control and Cd-treated. Treated rats were intraperitoneal injected with 1 mg/kg body weight cadmium chloride (CdCl2) for 4 weeks (5 P.M each day for 6 days/week). At the end of the exposure period, liver tissue samples were processed into ultrathin sections for analysis of advanced analytical transmission electron microscopy and X-ray energy dispersive spectroscopy (TEM/X-EDS) investigations. Ultrastructural images and X-ray energy dispersive spectrum were acquired at microscale. RESULTS: Cd can cause changes in the structure of the organelle, including the collapse of the membrane structure in the cell, the destruction of the internal structure of the organelle, the mitochondrial swelling, the expansion of the endoplasmic reticulum, and the appearance of inclusions. Cadmium bioaccumulation is detected in the mitochondria at microscale by TEM/X-EDS, which is the visual evidence of morphological changes of mitochondria related to Cd. CONCLUSION: The combination of detailed ultrastructure and microscale X-ray energy dispersive spectroscopy (X-EDS) characterization of cadmium hepatotoxicity demonstrate that cadmium indeed leads to mitochondrial damage, which is helpful for further investigation of the pathological mechanism of cadmium hepatotoxicity.

Kinetics of Au-Ga Droplet Mediated Decomposition of GaAs Nanowires.

Particle-assisted III-V semiconductor nanowire growth and applications thereof have been studied extensively. However, the stability of nanowires in contact with the particle and the particle chemical composition as a function of temperature remain largely unknown. In this work, we use in situ transmission electron microscopy to investigate the interface between a Au-Ga particle and the top facet of an ⟨1̅1̅1̅⟩-oriented GaAs nanowire grown via the vapor-liquid-solid process. We observed a thermally activated bilayer-by-bilayer removal of the GaAs facet in contact with the liquid particle during annealing between 300 and 420 °C in vacuum. Interestingly, the GaAs-removal rates initially depend on the thermal history of the sample and are time-invariant at later times. In situ X-ray energy dispersive spectroscopy was also used to determine that the Ga content in the particle at any given temperature remains constant over extended periods of time and increases with increasing temperature from 300 to 400 °C. We attribute the observed phenomena to droplet-assisted decomposition of GaAs at a rate that is controlled by the amount of Ga in the droplet. We suggest that the observed transients in removal rates are a direct consequence of time-dependent changes in the Ga content. Our results provide new insights into the role of droplet composition on the thermal stability of GaAs nanowires and complement the existing knowledge on the factors influencing nanowire growth. Moreover, understanding the nanowire stability and decomposition is important for improving processing protocols for the successful fabrication and sustained operation of nanowire-based devices.

Nanoencapsulation of arsenate with nanoscale zero-valent iron (nZVI): A 3D perspective.

The principal forces driving the efficient enrichment and encapsulation of arsenic (As) into nanoscale zero-valent iron (nZVI) are the disordered arrangement of the atoms and the gradient chemical potentials within the core-shell interface. The chemical compositions and the fine structure of nZVI are characterized with a combination of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM), X-ray energy-dispersive spectroscopy (XEDS), electron energy loss spectroscopy (EELS), and high-resolution X-ray photoelectron spectroscopy (HR-XPS). Atomically resolved EELS at the oxygen K-edge unfolds that the Fe species in nZVI are well stratified from Fe(III) oxides in the outermost periphery to a mixed Fe(III)/Fe(II) interlayer, then Fe(II) oxide and the pure Fe(0) phase. Reactions between As(V) and nZVI suggest that a well-structured local redox gradient exists within the shell layer, which serves as a thermodynamically favorable conduit for electron transfer from the iron core to the surface-bound As(V). HR-XPS with ion sputtering shows that arsenic species shift from As(V), As(III)/As(V) to As(V)/As(III)/As(0) from the iron oxide shell-water interface to the Fe(0) core. Results reinforce previous work on the efficacy of nZVI for removing and remediating arsenic while the analytical TEM methods are also applicable to the study of environmental interfaces and surface chemistry.

Physical Properties and Chemical Characterization of Two Experimental Epoxy Resin Root Canal Sealers.

INTRODUCTION: The aim of this in vitro study was to evaluate the setting time, flow, film thickness, solubility, radiopacity and characterization analysis of three epoxy resin based sealers including two experimental sealers and AH-26. METHODS AND MATERIALS: Five samples of each material were evaluated for setting time, flow, film thickness, solubility and radiopacity according to ISO 6876 Standard. Characterization of sealers was performed under the scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Statistical evaluation was performed using the Kruskal-Wallis test. RESULTS: In this study, AH-26 showed more radiopacity and flow compared to two other experimental sealers (P<0.05). However, both sealers had lower setting time than AH-26 (P<0.05). No statistical differences were found regarding film thickness, solubility and radiopacity (P>0.05). The characterization analysis exhibited relatively similar microstructure of AH-26 sealer to the experimental root canal sealers. CONCLUSION: According to the result of this study, all tested root canal sealers had acceptable properties based on ISO 6876 standard criteria.

Strontium Ranelate Effect on the Repair of Bone Defects and Molecular Components of the Cortical Bone of Rats

Abstract This study was conducted to evaluate the effects of treatment with strontium ranelate (SR) on the repair of bone defects and molecular components of bones in femurs. Adult female rats (n=27) were subjected to ovariectomy (OVX) or Sham surgery. Thirty days after surgery, a defect was made in the femur and the animals were then divided into three groups: OVX, SHAM and OVX+SR. Euthanasia was performed four weeks after the bone defect surgery. Repair in bone defect was assessed by computed microtomography (μCT) and chemical composition of cortical bone was analyzed by Fourier transform infrared (FTIR) spectroscopy and energy dispersive X-ray spectroscopy (EDS). The trabecular thickness (Tb.Th) of the newly formed bone in the OVX+SR group was significantly higher than that for the OVX group. The collagen maturity in the OVX+SR group was smaller than in the other two groups. In this group, a significant increase in the amount of strontium (Sr) and a decrease in the amount of calcium (Ca) embedded to bone tissue were also observed. Systemic treatment with SR improved microarchitecture of the newly formed bone inside the defect, but decreased cross-linking of mature collagen in cortical bone.

Resumo Este estudo foi conduzido para avaliar os efeitos do tratamento com ranelato de estrôncio (RE) na reparação de defeitos ósseos e componentes moleculares de ossos nos fêmures. Ratas adultas (n = 27) foram submetidas a ovariectomia (OVX) ou cirurgia Sham. Trinta dias após a cirurgia, um defeito foi feito no fêmur e os animais foram então divididos em três grupos: OVX, SHAM e OVX+RE. A eutanásia foi realizada quatro semanas após a cirurgia de preparo do defeito ósseo. A reparação do defeito ósseo foi avaliada por microtomografia computorizada (μCT) e a composição química do osso cortical foi analisada por espectroscopia de infravermelho de transformada de Fourier (FTIR) e espectroscopia por energia dispersiva de raios X (EDS). A espessura do osso trabecular (Tb.Th) recém formado no grupo OVX+SR foi significativamente maior que a do grupo OVX. A maturidade do colágeno no grupo OVX+SR foi menor do que nos outros dois grupos. Neste grupo, observou-se também um aumento significativo na quantidade de estrôncio (Sr) e uma diminuição na quantidade de cálcio (Ca) no tecido ósseo. O tratamento sistêmico com RE melhorou a microarquitetura do osso recém formado dentro do defeito, mas diminuiu a reticulação do colágeno maduro no osso cortical.

Preserving fibre health: reducing oxidative stress throughout the life of the hair fibre.

Hair health is an important attribute to women globally--specifically attributes such as shine, healthy tips, frizz-free and strength. However, many women will claim to have at least moderate hair damage caused by habits and practices such as washing, combing and brushing, use of heated implements and regular use of chemical treatments. The objective of this work was to investigate two mechanisms of damage--hair colouring and UV exposure--where oxidative processes are involved. The role of copper in these oxidative processes was then investigated: its presence in hair and its consequent impact on hair damage via free radical formation. Finally, the role of chelants N,N'-ethylene diamine disuccinic acid (EDDS) and histidine in preventing free radical formation was investigated and shown to improve hair health.

Advanced hair damage model from ultra-violet radiation in the presence of copper.

OBJECTIVE: Damage to hair from UV exposure has been well reported in the literature and is known to be a highly complex process involving initiation via absorption of UV light followed by formation and propagation of reactive oxygen species (ROS). The objective of this work was to understand these mechanisms, explain the role of copper in accelerating the formation of ROS and identify strategies to reduce the hair damage caused by these reactive species. METHODS: The location of copper in hair was measured by Transmission electron microscopy-(TEM) X-ray energy dispersive spectroscopy (XEDS) and levels measured by ICP-OES. Protein changes were measured as total protein loss via the Lowry assay, and MALDI ToF was used to identify the biomarker protein fragments. TBARS assay was used to measure lipid peroxide formation. Sensory methods and dry combing friction were used to measure hair damage due to copper and UV exposure and to demonstrate the efficacy of N,N' ethylenediamine disuccinic acid (EDDS) and histidine chelants to reduce this damage. RESULTS: In this work, a biomarker protein fragment formed during UV exposure is identified using mass spectrometry. This fragment originates from the calcium-binding protein S100A3. Also shown is the accelerated formation of this peptide fragment in hair containing low levels of copper absorbed from hair during washing with tap water containing copper ions. Transmission electron microscopy (TEM) X-ray energy dispersive spectroscopy (XEDS) studies indicate copper is located in the sulphur-poor endo-cuticle region, a region where the S100A3 protein is concentrated. A mechanism for formation of this peptide fragment is proposed in addition to the possible role of lipids in UV oxidation. A shampoo and conditioner containing chelants (EDDS in shampoo and histidine in conditioner) is shown to reduce copper uptake from tap water and reduce protein loss and formation of S100A3 protein fragment. In addition, the long-term consequences of UV oxidation and additional damage induced by copper are illustrated in a four-month wear study where hair was treated with a consumer relevant protocol of hair colouring treatments, UV exposure and regular shampoo and conditioning. CONCLUSIONS: The role of copper in accelerating UV damage to hair has been demonstrated as well as the ability of chelants such as EDDS and histidine in shampoo and conditioner products to reduce this damage.

Removal of selenium from water with nanoscale zero-valent iron: mechanisms of intraparticle reduction of Se(IV).

Increasing evidences suggest that nanoscale zero-valent iron (nZVI) is an effective agent for treatment and removal of selenium from water. For example, 1.3 mM selenite was quickly removed from water within 3 min with 5 g/L nZVI. In this work, reaction mechanisms of selenite [Se(IV)] in a single core-shell structured nanoscale zero-valent iron (nZVI) particle were studied with the method of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) integrated with X-ray energy dispersive spectroscopy (XEDS). This method was utilized to visualize solid phase translocation and transformation of Se(IV) such as diffusion, reduction, deposition and the effect of surface defects in a single nanoparticle. Se(IV) was reduced to Se(-II) and Se(0), which then formed a 0.5 nm layer of selenium at the iron oxide-Fe(0) interface at a depth of 6 nm from the surface. The results provided near atomic-resolution proof on the intraparticle diffusion-reduction of Se(IV) induced by nZVI. The STEM mapping also discovered that defects on the surface layer accelerate the diffusion of selenium and increase the capacity of nZVI for selenium sequestration.

Naringin accelerates the regression of pre-neoplastic lesions and the colorectal structural reorganization in a murine model of chemical carcinogenesis.

The aim of this study was to investigate the effect of Naringin on pre-neoplastic colorectal lesions induced by chemical carcinogen in rats. Female Wistar rats weighing 130.8±27.1 g received weekly one subcutaneous injection of 1,2-dimethylhydrazine (DMH, 20 mg/kg) for 10 weeks. The animals were divided into 5 groups with 6 animals in each group. Group 1: 0.9% saline; Group 2: DMH+0.9% saline; Group 3: DMH+Naringin (10 mg/kg); Group 4: DMH+Naringin (100 mg/kg); Group 5: DMH+Naringin (200 mg/kg). G2 and G3 showed a significant increase in ACF number, AgNOR/nucleus and mitosis compared to G1. G4 and G5 presented a significant reduction in these parameters compared to G2. The number of cells producing acidic and neutral mucins, red blood cells and the level of antioxidant minerals, such as copper, magnesium, selenium and zinc, were significantly reduced in G2 and G3, but similar in G4 and G5 compared to G1. Naringin, especially at 200 mg/kg, was effective in reducing the number of pre-neoplastic lesions in rats exposed to DMH. Some of these effects may be due to reduction in cellular proliferation and tissue levels of iron together with the recovery of antioxidant mineral levels induced by this flavonoid.

Formation and characteristics of crystals on the surface of mineral trioxide aggregate in vitro / 实用口腔医学杂志

Objective:To examine the surface of mineral trioxide aggr eg ate (MTA) when treated in different conditions in vitro. Method: Root blocks were prepared. MTA and other three dental materials (Dycal, Dyr act and amalgam) were respectively filled into the root canals of prepared root blocks. The roots with the materials were maintained in distilled water or simul ated body fluid (SBF) at 37 ℃ for 5 days. Scanning electron microscopy(SEM) and X-ray energy dispersive spectroscopy(EDS) were employed to investigate the mor phological changes and chemical components. Results:There was pr ecipitate of simple crystal units or crystalline structure in the MTA specimens. EDS showed one or two peaks corresponding to calcium or calcium and phosphorus. Conclusions:Apatite may produce and grew by MTA on its surface.