Impact of toxicity effects of zinc oxide nanoparticles in rats within acute and subacute experiments

Introduction. Occupational air is contaminated with zinc oxide nanoparticles in the copper smelting industry, especially in the smelting of brass and copper. A wide range of toxic effects with varied clinical symptomatology is observed in zinc and its compounds. Competitive relations with many other metals, including calcium, copper, and iron, are the foundation of most cases of zinc intoxication. Long-term administration of zinc or its compounds to laboratory rodents affects enzymes, carbohydrates and mineral metabolism. Materials and methods. Subchronic intoxication with repeated intraperitoneal injections and acute low respiratory tract reaction to a single intratracheal injection of zinc nanoparticles were simulated in outbred white rats. Water suspensions of zinc oxide nanoparticles with a 30-80 nm diameter were applied in both experimental models. Upon completion of the exposure, the condition of the rats in all groups was evaluated in many generally accepted criteria for toxicity. The student’s t-test was applied for statistical analysis of the obtained data. Results. Moderate intoxication development in a subchronic experiment is demonstrated. Homogeneous ultrastructural changes in the spleen tissue were revealed. Mitochondrial damage with partial or complete loss of crista is the most common. The fragmentation ratio of DNA was found by a statistically significant increase. A single intratracheal injection of zinc oxide nanoparticles revealed the increase in the attraction of cells capable of their phagocytosis (mainly neutrophils) into the low respiratory tract. This shows their cytotoxicity. Conclusion. Moderate general toxic and cytotoxic effects of zinc oxide nanoparticles on the rat body were identified.

Cytotoxic action reduction of crystalline silicon dioxide in a toxicological experiment associated with Lymphomyosot

Introduction. Among the most relevant issues in occupational health is the risk management of the contamination of working air by crystalline silicon dioxide (CSD) in enterprises dealing with its extraction and processing. Cytotoxicity of this silicon type that underlies its fibrogenic action is of particular concern. Thereby, it is an urgent goal to find drugs that increase the body’s resistance to cytotoxic effects of silicon dioxide. Materials and methods. For the study of changes in the cellular composition of the bronchoalveolar lavage (BAL) and some of its biochemical characteristics, a respirable portion of Pervouralsk quartzite (PQ) containing 98% CSD was inserted intratracheally to outbred white female rats in the form of a suspension of 10 mg of PQ in 1 ml of distilled water in the dose of 1 ml. Student’s t-test was applied for statistical analysis of the obtained data. Results. PQ sample induces the alveolar phagocytosis response typical for cytotoxic dust expressed by an increase in the total BAL cell count, the number of both alveolar macrophages (AM) and neutrophilic leukocytes (NL), and particularly the NL/AM ratio (which is a reliable comparative index of cytotoxicity). The administration of «Lymphomyosot» considerably reduced this cytotoxic effect of PQ within one month before the intratracheal injection. It showed a decrease in NL/AM ratio and some biochemical indicators of cytolysis in BAL. Conclusion. There was demonstrated the applicability of «Lymphomyosot» as a precaution against the cytotoxic effect of CSD dust.

Role of the TSLP–DC–OX40L pathway in asthma pathogenesis and airway inflammation in mice

This study aimed to explore the effect of the TSLP–DC–OX40L pathway in asthma pathogenesis and airway inflammation in mice. For this, 65 male BALF/c mice were distributed among the control, asthma, immunoglobulin G (IgG) + asthma (IgG, 500 μg/500 μL, intratracheal injection of 50 μL each time), LY294002 (OX40L inhibitor) + asthma (intratracheal injection of 2 mg/kg LY294002), and anti-TSLP + asthma (intratracheal injection of 500 μg/500 μL TSLP antibody, 50 μL each time) groups. ELISA was applied to measure the serum levels of immunoglobulin E (IgE), ovalbumin (OVA)-sIgE, interleukin-4 (IL-4), IL-5, IL-13, and interferon-γ (IFN-γ); flow cytometry was employed to detect Treg cells and dendritic cell (DC) and lymphopoiesis. RT–qPCR and Western blot assays were used to measure the levels of TSLP, OX40L, T-bet, GATA-3, NF-κB, p38, and ERK. Treatment with LY294002 and anti-TSLP resulted in increases in the numbers of total cells, eosinophils, neutrophils, and lymphocytes in the bronchoalveolar lavage fluid; total serum levels of IgE, OVA-sIgE, IL-4, IL-5, and IL-13; levels of DC cells; lymphopoiesis; and levels of TSLP, OX40L, GATA-3, NF-κB, p38, and ERK, whereas there were decreases in the levels of IFN-γ and CD4+CD25+Treg cells; CD4+Foxp3+Treg cells; and T-bet. The TSLP–DC–OX40L pathway may contribute to asthma pathogenesis and airway inflammation by modulating the levels of CD4+CD25+Treg cells and inflammatory cytokines.

PLUTONIUM-239 DIOXIDE IN THE LUNG. Report 2: Pathology of the lungs of rats induced by intratracheal injection of plutonium-239 dioxide

Purpose: The study of lung pathology induced by intratracheal injection of plutonium-239 dioxide and obtaining actual data on the dose-dependent profile of the remote consequences. Material and methods: The plutonium dioxide was introduced into nonlinear white male rats once intratracheally in the amount of 100 kBq/kg body weight. Experimental animals were observed during their whole life. Radiometric, histoautoradiographical, histological and statistical research methods were used. Indicators of lung pathology were inflammatory, sclerotic, precancerous and neoplastic changes in the lungs. Results: The calculation of absorbed doses in the lungs showed their variety from 1 to 400 Gr. The paper presents a quantitative analysis of remote lung pathology according to the groups with average absorbed doses from 7 to 306 Gy. The introduction of 239PuO2 significantly increased the frequency of sclerotic changes of the lungs compared with intact rats (11 and 46 % respectively). Tumors were found in the lungs of 20 % of intact rats and of 51 % of the rats that received 239PuO2. Malignant neoplasm of epithelial origin prevailed. They were formed in 9 % of the biological control rats and in 41 % of the rats, carriers of 239PuO2. The dependence of the frequency of pathological changes in the lungs from absorbed dose in the organ was revealed. Conclusion: A single intratracheal introduction of 239PuO2 has increased the frequency of pathological changes in the lungs of rats compared with intact animals. With the increase of the absorbed dose in the lungs the number of rats with pneumosclerosis, tumors of epithelial origin and multiple tumors has grown. Most indicative are adenocarcinoma and squamous-cell carcinomas. With the increasing of absorbed dose not only the frequency, but a spectrum of tumors varies. Dose response – probability of effect for each type of non-neoplastic and neoplastic pathology has its own character. For tumors of hematopoietic and lymphoid tissue, localized in the lungs, the opposite from tumors of epithelial origin, dependence of the frequency of their formation from the absorbed dose has been revealed.

A novel method for intratracheal injection of infectious agents into mice

Intratracheal injection is a traditional technique used in small animal studies of highly contagious airborne pathogens such as Mycobacterium tuberculosis. However, current techniques of intratracheal injection generally involve procedures that pose a risk of incident injury and infection for researchers, and may also cause collateral damage to experimental animals during the installation process. Here we describe an intratracheal injection method that was enabled by a three dimensional printing of a custom platform. This updated technique improved the overall ergonomics of intratracheal injection in mice, minimizing the risk of human injury and implementing the 3R (replacement, reduction and refinement) principle in mouse infection studies.