Comparative absorption, distribution, and excretion of titanium dioxide and zinc oxide nanoparticles after repeated oral administration

Background The in vivo kinetics of nanoparticles is an essential to understand the hazard of nanoparticles. Here, the absorption, distribution, and excretion patterns of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles following oral administration were evaluated. Methods Nanoparticles were orally administered to rats for 13 weeks (7 days/week). Samples of blood, tissues (liver, kidneys, spleen, and brain), urine, and feces were obtained at necropsy. The level of Ti or Zn in each sample was measured using inductively coupled plasma-mass spectrometry. Results TiO2 nanoparticles had extremely low absorption, while ZnO nanoparticles had higher absorption and a clear dose-response curve. Tissue distribution data showed that TiO2 nanoparticles were not significantly increased in sampled organs, even in the group receiving the highest dose (1041.5 mg/kg body weight). In contrast, Zn concentrations in the liver and kidney were significantly increased compared with the vehicle control. ZnO nanoparticles in the spleen and brain were minimally increased. Ti concentrations were not significantly increased in the urine, while Zn levels were significantly increased in the urine, again with a clear dose-response curve. Very high concentrations of Ti were detected in the feces, while much less Zn was detected in the feces. Conclusions Compared with TiO2 nanoparticles, ZnO nanoparticles demonstrated higher absorption and more extensive organ distribution when administered orally. The higher absorption of ZnO than TiO2 nanoparticles might be due to the higher dissolution rate in acidic gastric fluid, although more thorough studies are needed

A New and Versatile Synthesis of 1,3-Dioxan-5-yl-pyrimidine and Purine Nucleoside Analogues

1,3-Dioxan-5-yl pyrimidine and purine nucleoside analogues were prepared following a new and versatile synthetic strategy. These analogues were synthesized via nucleophilic addition of the selected nucleobase to a 1,3-dioxane scaffold that presents an appropriate leaving group in position 5. In particular cis and trans isomers of purine/pyrimidine nucleosides and their halogenated homologues were obtained. NMR experiments, carried out on the cis isomers, led to assignment of an equatorial orientation to the 2-hydroxymethyl group and axial orientation to the nucleobase in position 5 of the 1,3-dioxane. The trans isomers showed a diequatorial orientation of these groups. These assignments were confirmed by X-ray crystallographic studie

Assess the expression of ubiquitin specific protease USP2a for bladder cancer diagnosis

Background: Given that a deubiquitinating enzyme, ubiquitin-specific protease 2a (USP2a), regulates ubiquitination, trafficking, and degradation of EGFR, which plays a critical role in bladder cancer, in this study, we aimed to quantify the USP2a gene expression, and to determine the possibility that USP2a can be used for bladder cancer diagnosis. Methods: Using two independent cohorts (cohort 1, n = 339 in total; cohort 2, n = 140 in total) consisting of human bladder tissues from BC patients and normal controls, we analyzed the gene expression levels of USP2a. A quantitative real-time PCR amplification was performed using a Rotor Gene 6000 instrument to quantify the expression of USP2a mRNA. Results: A comparison of 305 bladder cancers and 34 age-matched controls showed an 81.4 % reduction in USP2a expression in bladder cancers as compared to normal bladder tissues (p < 0.001). In the independent cohort consisting of 140 BC tissues and matched adjacent normal bladder tissues, the levels of USP2a in the specimens of BC patients were reduced by 86.9 % as compared to matched surrounding normal specimens from the same patients (p < 0.001). Furthermore, there was 36.3 % reduction of USP2a gene expression in muscle invasive bladder cancer (MIBC, n = 121), compared to non muscle invasive bladder cancer (NMIBC, n = 184) (p = 0.004). Lastly, USP2a mRNA expression was significantly reduced in higher stages of MIBC patients (p = 0.024), but not in NMIBC patients. Conclusions: Our findings suggest that USP2a mRNA may be considered as a diagnostic marker candidate for bladder cancer, in particular, to stratify MIBC patients with a more invasive phenotype

Predictive value of in vitro assays depends on the mechanism of toxicity of metal oxide nanoparticles

BACKGROUND: Hazard identification for risk assessment of nanoparticles (NPs) is mainly composed of in vitro cell-based assays and in vivo animal experimentation. The rapidly increasing number and functionalizations of NPs makes in vivo toxicity tests undesirable on both ethical and financial grounds, creating an urgent need for development of in vitro cell-based assays that accurately predict in vivo toxicity and facilitate safe nanotechnology. METHODS: In this study, we used 9 different NPs (CeO(2), TiO(2), carbon black, SiO(2), NiO, Co(3)O(4), Cr(2)O(3), CuO, and ZnO). As an in vivo toxicity endpoint, the acute lung inflammogenicity in a rat instillation model was compared with the in vitro toxicity endpoints comprising cytotoxicity, pro-inflammatory cytokine expression, or haemolytic potential. For in vitro assays, 8 different cell-based assays were used including epithelial cells, monocytic/macrophage cells, human erythrocytes, and combined culture. RESULTS: ZnO and CuO NPs acting via soluble toxic ions showed positive results in most of assays and were consistent with the lung inflammation data. When compared in in vitro assays at the same surface area dose (30 cm(2)/mL), NPs that were low solubility and therefore acting via surface reactivity had no convincing activity, except for CeO(2) NP. Cytotoxicity in differentiated peripheral blood mononuclear cells was the most accurate showing 89% accuracy and 11% false negativity in predicting acute lung inflammogenicity. However, the haemolysis assay showed 100% consistency with the lung inflammation if any dose, having statistical significance was considered positivity. Other cell-based in vitro assays showed a poorer correlation with in vivo inflammogenicity. CONCLUSIONS: Based on the toxicity mechanisms of NPs, two different approaches can be applied for prediction of in vivo lung inflammogenicity. Most in vitro assays were good at detecting NPs that act via soluble ions (i.e., ZnO and CuO NP). However, in vitro assays were limited in detecting NPs acting via surface reactivity as their mechanism of toxicity, except for the haemolysis assay

Subchronic inhalation toxicity of gold nanoparticles

<p>Abstract</p> <p>Background</p> <p>Gold nanoparticles are widely used in consumer products, including cosmetics, food packaging, beverages, toothpaste, automobiles, and lubricants. With this increase in consumer products containing gold nanoparticles, the potential for worker exposure to gold nanoparticles will also increase. Only a few studies have produced data on the <it>in vivo </it>toxicology of gold nanoparticles, meaning that the absorption, distribution, metabolism, and excretion (ADME) of gold nanoparticles remain unclear.</p> <p>Results</p> <p>The toxicity of gold nanoparticles was studied in Sprague Dawley rats by inhalation. Seven-week-old rats, weighing approximately 200 g (males) and 145 g (females), were divided into 4 groups (10 rats in each group): fresh-air control, low-dose (2.36 × 10⁴particle/cm³, 0.04 μg/m³), middle-dose (2.36 × 10⁵particle/cm³, 0.38 μg/m³), and high-dose (1.85 × 10⁶particle/cm³, 20.02 μg/m³). The animals were exposed to gold nanoparticles (average diameter 4-5 nm) for 6 hours/day, 5 days/week, for 90-days in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and lung function were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry tests, and organ weights were measured. Cellular differential counts and cytotoxicity measurements, such as albumin, lactate dehydrogenase (LDH), and total protein were also monitored in a cellular bronchoalveolar lavage (BAL) fluid. Among lung function test measurements, tidal volume and minute volume showed a tendency to decrease comparing control and dose groups during the 90-days of exposure. Although no statistically significant differences were found in cellular differential counts, histopathologic examination showed minimal alveoli, an inflammatory infiltrate with a mixed cell type, and increased macrophages in the high-dose rats. Tissue distribution of gold nanoparticles showed a dose-dependent accumulation of gold in only lungs and kidneys with a gender-related difference in gold nanoparticles content in kidneys.</p> <p>Conclusions</p> <p>Lungs were the only organ in which there were dose-related changes in both male and female rats. Changes observed in lung histopathology and function in high-dose animals indicate that the highest concentration (20 μg/m³) is a LOAEL and the middle concentration (0.38 μg/m³) is a NOAEL for this study.</p

Interlaboratory comparison study of the Colony Forming Efficiency assay for assessing cytotoxicity of nanomaterials

Nanotechnology has gained importance in the past years as it provides opportunities for industrial growth and innovation. However, the increasing use of manufactured nanomaterials (NMs) in a number of commercial applications and consumer products raises also safety concerns and questions regarding potential unintended risks to humans and the environment. Since several years the European Commission’s Joint Research Centre (JRC) is putting effort in the development, optimisation and harmonisation of in vitro test methods suitable for screening and hazard assessment of NMs. Work is done in collaboration with international partners, in particular the Organisation for Economic Co-operation and Development (OECD). This report presents the results from an interlaboratory comparison study of the in vitro Colony Forming Efficiency (CFE) cytotoxicity assay performed in the frame of OECD's Working Party of Manufactured Nanomaterials (WPMN). Twelve laboratories from European Commission, France, Italy, Japan, Poland, Republic of Korea, South Africa and Switzerland participated in the study coordinated by JRC. The results show that the CFE assay is a suitable and robust in vitro method to assess cytotoxicity of NMs. The assay protocol is well defined and is easily and reliably transferable to other laboratories. The results obtained show good intra and interlaboratory reproducibility of the assay for both the positive control and the tested nanomaterials. In conclusion the CFE assay can be recommended as a building block of an in vitro testing battery for NMs toxicity assessment. It could be used as a first choice method to define dose-effect relationships for other in vitro assays.JRC.I.4-Nanobioscience