Masayuki Ohyama

A Comparison of the Production of Reactive Oxygen Species by Suspended Particulate Matter and Diesel Exhaust Particles with Macrophages

Oxidative stress has emerged as a pivotal mechanism that underlies the toxic pulmonary effects of suspended particulate matter (SPM). Experimental evidence shows that redox-active transition metals, redox-cycling quinoids, and polycyclic aromatic hydrocarbons (PAHs) contained in SPM act synergistically, producing reactive oxygen species (ROS). The direct production of superoxide anion and the damaging hydroxyl radical has been studied in aqueous and dimethyl sulfoxide (DMSO) suspensions of SPM both with and without H2O2; however, no study has reported on the release of ROS from ingesting macrophages with SPM. We investigated the time course of the ability to induce lucigenin-dependent chemiluminescence (CL) from human monocyte-derived macrophages exposed to SPM, carbon black particles, and diesel exhaust particles (DEP). We also examined hydroxyl radical generation from the same experimental system using the 2-deoxy-d-robse method. We found an increase of CL for SPM, but not for carbon black particles or for DEP. Hydroxyl radical generation was observed in both SPM and DEP, but the release from DEP was more frequent than that from SPM. These results suggest that certain components of SPM are important in the response of ROS from ingesting macrophages with SPM, and that those components are discharged from SPM into the atmosphere.

Effects of nitrous acid exposure on pulmonary tissues in guinea pigs

Many epidemiological studies on the effects of nitrogen dioxide (NO2) on respiratory function may have included nitrous acid (HONO) exposures in their measures, because conventional NO2 assays detect HONO as NO2. A few epidemiological studies and human HONO inhalation experiments have associated HONO with decrements in lung functions. However, there have been few HONO exposure experiments in animals. This study aims to develop a HONO generation system for the animal exposure experiments, and to assess the association of HONO exposure with histopathologic alterations in the respiratory tract of guinea pigs. We exposed the guinea pigs to 3.6 ppm HONO with secondary products of 0.3 ppm NO2 and 1.6 ppm nitric oxide (NO) for 4 weeks (24 h/day). We conducted histopathologic analyses and measured specific airway resistance (sRaw) from 7 h 40 min to 8 h 30 min after the end of HONO exposure. We found pulmonary emphysema-like alterations in the alveolar duct centriacinar regions, distortion of the centriacinar regions of alveolar ducts with extension of the bronchial epithelial cells and smooth muscle cells, and expansion of bronchial epithelial cells, in the HONO exposure. These histopathologic results suggest that a high concentration of HONO with some NO2 and NO may associate with decrements in lung functions and some respiratory symptoms. Although the increased tendency of the sRaw value was observed in the HONO exposure group, no statistically significant difference was found between the sRaw values from the HONO exposure group and the filtered air group (p = 0.06, student’s t-test).

Histological Effect of Nitrous Acid with Secondary Products of Nitrogen Dioxide and Nitric Oxide Exposure on Pulmonary Tissue in Mice

Numerous epidemiological studies of respiratory effects of nitrogen dioxide may have included exposures to nitrous acid, because conventional assays of nitrogen dioxide measure nitrous acid as nitrogen dioxide. A few epidemiological studies and human inhalation experiments of nitrous acid reported that nitrous acid is associated with decrements in lung function and possibly with respiratory symptoms. Moreover, our guinea pig exposure experiment of nitrous acid demonstrated that nitrous acid inducible the pulmonary emphysema-like disease and the architecture alterations of the alveolar duct centriacinar regions with the thickened interstitium. The purpose of this study was to assess the acute toxicity and the injury of exposure to nitrous acid with histopathological alterations in the respiratory tract in mice. We continuously exposed only filtered air and the filtered air with 8.4 ppm nitrous acid with secondary products of 2.8 ppm nitrogen dioxide and 7.2 ppm nitric oxide (24 hr/day) to two mice groups (n=5) for 3 weeks. We conducted histopathological analyses. We found the hyperplasia of the terminal bronchial epithelial cells with the meandering irregularly and without dysplasia in nitrous acid mice exposure group. In nitrous acid mice exposure group, we did not observe the architectural alterations such as the emphysema-like alterations which we have observed in our guinea pig exposure experiment of 3.6 ppm nitrous acid. Moreover, the collagen bundles and thickened interstitium were also indistinct in the alveolar duct centriacinar regions in this concentration of nitrous acid exposure to mice. These histopathological results suggest that the injury effects of HONO were weak.

Effects of Atmospheric Particles and Several Model Particles of Particulate Matter Components on Human Monocyte-Derived Macrophage Oxidative Responses

1Department of Environmental Health, Osaka Prefectural Institute of Public Health, Osaka, Japan 2Department of Planning and Coordination, Osaka Prefectural Institute of Public Health, Osaka, Japan 3Department of Virology, Osaka Prefectural Institute of Public Health, Osaka, Japan 4Department of Work Environment Research Group, Japanese National Institute of Occupational Safety and Health, Kawasaki, Japan 5Department of Environmental Health, Korea University, Seoul, Korea 6Department of Institute of Medical, Pharmaceutical and Health Sciences, Faculty of Pharmacy, Kanazawa University, Kanazawa, Japan 7Department of Public Health, Sagami Women’s University, Sagamihara, Japan

Effects of nitrous acid exposure on baseline pulmonary resistance and Muc5ac in rats

Abstract We examined the baseline pulmonary resistance (RLung), baseline dynamic lung compliance (Cdyn), cytokine inductions, and histological alterations in rats exposed to nitrous acid (HONO) with secondary products of nitrogen dioxide (NO2) and nitric oxide (NO) to assess its biological effects. We exposed three groups of nine male F344 rats to different doses of HONO for six weeks (24 h/day). The cumulative values of HONO concentration were measured twice. The average concentrations of nitrogen oxide for each group were 5.8 parts per million (ppm) HONO with secondary products of 0.7 ppm NO2 and 2.3 ppm NO, 4.1 ppm HONO with 0.1 ppm NO2 and 0.6 ppm NO, and a clean air control. We measured baseline RLung and baseline Cdyn using tracheal cannulation. A tracheal tube was inserted into the trachea by tracheostomy, and lung function measurements (baseline RLung and baseline Cdyn) were conducted in mechanically ventilated rats. We measured mRNA levels of Cxcl-1, TNF-α, and Muc5ac in the right lung using quantitative RT-PCR, and observed histological alterations and the alveolar mean linear intercept (Lm) on the left lung. Our results demonstrated that HONO exposure significantly increased baseline RLung, Lm and Muc5ac expression, but did not affect baseline Cdyn or expression of Cxcl-1 and TNF-α. Further, we identified bronchial smooth muscle hypertrophy, pulmonary emphysema-like alterations in the alveolar duct centriacinar regions, and increased goblet cells in HONO-exposed rats. The present results suggest that HONO (with secondary products) adversely affects respiratory function, but that these pathologies may be unrelated to inflammation.

Background factors of chemical intolerance and parent–child relationships

BackgroundChemical intolerance is a widespread public health problem characterized by symptoms that reportedly result from low-level exposure to chemicals. Although several studies have reported factors related to chemical intolerance in adults, the impact of family members has not been reported. In the present study, we investigated the background factors related to chemical intolerance in family members and parent–child relationships.MethodsWe distributed a self-reported questionnaire to 4325 mothers who were invited to visit the Kishiwada Health Center in Kishiwada City, Osaka, between January 2006 and December 2007 for the regular health checkup of their three-and-a-half-year-old children.ResultsThe prevalence of chemical intolerance in the 3-year-old children was almost one eighteenth of that reported by their mothers. Multiple logistic regression analyses revealed that cold sensitivity [odds ratio (OR), 1.89; 95% confidence interval (CI), 1.04–3.44], past bronchial asthma (OR, 2.84; 95% CI, 1.46–5.53), and any past allergies (OR, 2.21; 95% CI, 1.36–3.60) were significantly associated with chemical intolerance in the mother. The presence of indoor cat during childhood (OR, 1.99; 95% CI, 1.08–3.69) was significantly associated with chemical intolerance in the mother; however, the association was weak compared with cold sensitivity and past asthma and allergies. The current chemical intolerance of the mother was significantly associated with allergic rhinitis (OR, 2.32; 95% CI, 1.19–4.53), bronchial asthma (OR, 3.66; 95% CI, 2.00–6.69), and chronic bronchitis (OR, 3.69; 95% CI, 1.04–13.03) in her 3-year-old child.ConclusionsThe results suggest that inherent physical constitution and childhood housing environment are associated with a risk of acquiring chemical intolerance. Children of mothers with chemical intolerance have a possible risk of respiratory hypersensitivity or inflammation. Further investigation is recommended to determine the inherent physical constitution and background environmental factors associated with the risk of acquiring chemical intolerance. The impact of having mothers with chemical intolerance on the health of children also requires further study.

Comparing Heat-treated Silica Particle with Silica Particles for the Ability to Induce Superoxide Release from Rat Alveolar Macrophages

Crystalline silica can devitrify with the formation of cristobalite and other crystalline silica species when exposed to prolonged high temperatures, which is of potential concern because crystalline silica is classified as carcinogenic. Silica particles activate macrophages to release oxidants, which contribute to inflammation and injury in the lower respiratory tract. Our aim was to compare silica particles with heat-treated silica particles for their ability to induce superoxide release from rat alveolar macrophages. We estimated the ability of four types of silica particle samples and heat-treated silica particles with different number average particle diameter to induce lucigenin-dependent chemiluminescence (CL) from macrophages based on the number of silica particles. A strong positive correlation was observed between particle diameter and the ability to induce CL in both the silica and heat-treated silica samples. Moreover, the ability of heat-treated silica samples to induce CL was approximately 43% of that of the silica samples. These results suggest that heat-treated silica reduces superoxide release from macrophages, and that the heat-treated reduces the biological effects of silica.

Development of a Gaseous Nitrous Acid Generation System for Animal Exposure Experiments

Although a flow-type generation system for obtaining gaseous nitrous acid (HONO) at parts-per-billion levels has already been reported, higher gaseous HONO concentrations on the order of parts per million (ppm) are necessary for use in animal exposure experiments, which are conducted to examine certain biological effects. We have developed a flow-type generation system to produce gaseous HONO at ppm levels for animal exposure experiments. This system is based on spraying a mixture of aqueous sodium nitrite with an acid in a porous polytetrafluoroethylene tube. Herein, we report the technical details and cautionary notes of the manufacturing of the system. The most technical cautionary note pertains the flow-control method in the tube for the gas and water solution.