Adverse Effect of Nano-Silicon Dioxide on Lung Function of Rats with or without Ovalbumin Immunization

BACKGROUND: The great advances of nanomaterials have brought out broad important applications, but their possible nanotoxicity and risks have not been fully understood. It is confirmed that exposure of environmental particulate matter (PM), especially ultrafine PM, are responsible for many lung function impairment and exacerbation of pre-existing lung diseases. However, the adverse effect of nanoparticles on allergic asthma is seldom investigated and the mechanism remains undefined. For the first time, this work investigates the relationship between allergic asthma and nanosized silicon dioxide (nano-SiO₂). METHODOLOGY/PRINCIPAL FINDINGS: Ovalbumin (OVA)-treated and saline-treated control rats were daily intratracheally administered 0.1 ml of 0, 40 and 80 µg/ml nano-SiO₂ solutions, respectively for 30 days. Increased nano-SiO₂ exposure results in adverse changes on inspiratory and expiratory resistance (Ri and Re), but shows insignificant effect on rat lung dynamic compliance (Cldyn). Lung histological observation reveals obvious airway remodeling in 80 µg/ml nano-SiO₂-introduced saline and OVA groups, but the latter is worse. Additionally, increased nano-SiO₂ exposure also leads to more severe inflammation. With increasing nano-SiO₂ exposure, IL-4 in lung homogenate increases and IFN-γ shows a reverse but insignificant change. Moreover, at a same nano-SiO₂ exposure concentration, OVA-treated rats exhibit higher (significant) IL-4 and lower (not significant) IFN-γ compared with the saline-treated rats. The percentages of eosinophil display an unexpected result, in which higher exposure results lower eosinophil percentages. CONCLUSIONS/SIGNIFICANCE: This was a preliminary study which for the first time involved the effect of nano-SiO₂ to OVA induced rat asthma model. The results suggested that intratracheal administration of nano-SiO₂ could lead to the airway hyperresponsiveness (AHR) and the airway remolding with or without OVA immunization. This occurrence may be due to the Th1/Th2 cytokine imbalance accelerated by the nano-SiO₂ through increasing the tissue IL-4 production

Expression analysis of asthma candidate genes during human and murine lung development

<p>Abstract</p> <p>Background</p> <p>Little is known about the role of most asthma susceptibility genes during human lung development. Genetic determinants for normal lung development are not only important early in life, but also for later lung function.</p> <p>Objective</p> <p>To investigate the role of expression patterns of well-defined asthma susceptibility genes during human and murine lung development. We hypothesized that genes influencing normal airways development would be over-represented by genes associated with asthma.</p> <p>Methods</p> <p>Asthma genes were first identified via comprehensive search of the current literature. Next, we analyzed their expression patterns in the developing human lung during the pseudoglandular (gestational age, 7-16 weeks) and canalicular (17-26 weeks) stages of development, and in the complete developing lung time series of 3 mouse strains: A/J, SW, C57BL6.</p> <p>Results</p> <p>In total, 96 genes with association to asthma in at least two human populations were identified in the literature. Overall, there was no significant over-representation of the asthma genes among genes differentially expressed during lung development, although trends were seen in the human (Odds ratio, OR 1.22, confidence interval, CI 0.90-1.62) and C57BL6 mouse (OR 1.41, CI 0.92-2.11) data. However, differential expression of some asthma genes was consistent in both developing human and murine lung, e.g. <it>NOD1, EDN1, CCL5, RORA </it>and <it>HLA-G</it>. Among the asthma genes identified in genome wide association studies, <it>ROBO1</it>, <it>RORA, HLA-DQB1, IL2RB </it>and <it>PDE10A </it>were differentially expressed during human lung development.</p> <p>Conclusions</p> <p>Our data provide insight about the role of asthma susceptibility genes during lung development and suggest common mechanisms underlying lung morphogenesis and pathogenesis of respiratory diseases.</p

Temperature dependence of FMR spectrum of Fe3C magnetic agglomerates

The sample of iron carbide has been prepared using carburisation of iron with ethylene/hydrogen mixture. After carburisation, the sample was characterized by using XRD and scanning electron microscopy. XRD revealed the presence of cementite phase only. The mean size of cementite crystallites was determined to be 46 nm. The FMR absorption signals have been investigated in the temperature range from liquid helium up to room temperature. The asymmetric, very broad and intense FMR line was registered and decomposed in two Lorentzian-shape components (low- and high-field). The main high-field component shifts toward low magnetic fields with decreasing temperature. At 75 K a phase transition was observed due to the freezing of the non-magnetic matrix. Additionally, the spin glass state was recorded below 30 K

XRD, TEM and magnetic resonance studies of iron carbide nanoparticle agglomerates in a carbon matrix

Three powder samples with different content of iron carbide in a carbon matrix have been synthesised by carburisation of nanocrystalline iron with methane. The samples have been characterised by XRD and TEM methods. The mean crystallite size of the obtained iron carbide has been found to be in the range from 41 to 67 nm. The magnetic resonance measurements of these samples have been performed at room temperature. Very intense magnetic resonance lines have been recorded for each of the samples. A resonance field, an integral intensity and a linewidth strongly depend on the concentration of iron carbide. The observed magnetic resonance lines have been fitted with two Lorentzian-shape lines, one centred at lower and the other at higher magnetic fields. Strong magnetic anisotropy was observed for all the samples and for the sample with lower concentration of iron carbide it is more intense. The resonance absorption signal arises from the agglomerates of iron carbide nanoparticles interacting strongly among themselves. The observed shift of the resonance field is connected with a strong ferromagnetic interaction between agglomerates of nanoparticles. © 2004 Elsevier Ltd. All rights reserved